talzoomanzoo/olympiadbench · Datasets at Hugging Face

Question stringlengths 49 4.42k	answer listlengths 1 1
Dan was born in a year between 1300 and 1400. Steve was born in a year between 1400 and 1500. Each was born on April 6 in a year that is a perfect square. Each lived for 110 years. In what year while they were both alive were their ages both perfect squares on April 7?	[ "1469" ]
Determine all values of $k$ for which the points $A(1,2), B(11,2)$ and $C(k, 6)$ form a right-angled triangle.	[ "1,3,9,11" ]
If $\cos \theta=\tan \theta$, determine all possible values of $\sin \theta$, giving your answer(s) as simplified exact numbers.	[ "$\\frac{-1+\\sqrt{5}}{2}$" ]
Linh is driving at $60 \mathrm{~km} / \mathrm{h}$ on a long straight highway parallel to a train track. Every 10 minutes, she is passed by a train travelling in the same direction as she is. These trains depart from the station behind her every 3 minutes and all travel at the same constant speed. What is the constant speed of the trains, in $\mathrm{km} / \mathrm{h}$ ?	[ "$\\frac{600}{7}$" ]
Determine all pairs $(a, b)$ of real numbers that satisfy the following system of equations: $$ \begin{aligned} \sqrt{a}+\sqrt{b} & =8 \\ \log _{10} a+\log _{10} b & =2 \end{aligned} $$ Give your answer(s) as pairs of simplified exact numbers.	[ "$(22+8 \\sqrt{6}, 22-8 \\sqrt{6})$,$(22-8 \\sqrt{6}, 22+8 \\sqrt{6})$" ]
A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ \left\|a_{1}-a_{2}\right\|+\left\|a_{3}-a_{4}\right\| $$ over all permutations $a_{1}, a_{2}, a_{3}, a_{4}$ of $1,2,3,4$.	[ "$\\frac{10}{3}$" ]
A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ a_{1}-a_{2}+a_{3}-a_{4}+a_{5}-a_{6}+a_{7} $$ over all permutations $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}, a_{7}$ of $1,2,3,4,5,6,7$.	[ "4" ]
A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ \left\|a_{1}-a_{2}\right\|+\left\|a_{3}-a_{4}\right\|+\cdots+\left\|a_{197}-a_{198}\right\|+\left\|a_{199}-a_{200}\right\| $$ over all permutations $a_{1}, a_{2}, a_{3}, \ldots, a_{199}, a_{200}$ of $1,2,3,4, \ldots, 199,200$. (The sum labelled (*) contains 100 terms of the form $\left\|a_{2 k-1}-a_{2 k}\right\|$.)	[ "6700" ]
If $0^{\circ}<x<90^{\circ}$ and $3 \sin (x)-\cos \left(15^{\circ}\right)=0$, what is the value of $x$ to the nearest tenth of a degree?	[ "$18.8^{\\circ}$" ]
The function $f(x)$ has the property that $f(2 x+3)=2 f(x)+3$ for all $x$. If $f(0)=6$, what is the value of $f(9)$ ?	[ "33" ]
Suppose that the functions $f(x)$ and $g(x)$ satisfy the system of equations $$ \begin{aligned} f(x)+3 g(x) & =x^{2}+x+6 \\ 2 f(x)+4 g(x) & =2 x^{2}+4 \end{aligned} $$ for all $x$. Determine the values of $x$ for which $f(x)=g(x)$.	[ "$5,-2$" ]
In a short-track speed skating event, there are five finalists including two Canadians. The first three skaters to finish the race win a medal. If all finalists have the same chance of finishing in any position, what is the probability that neither Canadian wins a medal?	[ "$\\frac{1}{10}$" ]
Determine the number of positive integers less than or equal to 300 that are multiples of 3 or 5 , but are not multiples of 10 or 15 .	[ "100" ]
In the series of odd numbers $1+3+5-7-9-11+13+15+17-19-21-23 \ldots$ the signs alternate every three terms, as shown. What is the sum of the first 300 terms of the series?	[ "-900" ]
A two-digit number has the property that the square of its tens digit plus ten times its units digit equals the square of its units digit plus ten times its tens digit. Determine all two-digit numbers which have this property, and are prime numbers.	[ "11,19,37,73" ]
A lead box contains samples of two radioactive isotopes of iron. Isotope A decays so that after every 6 minutes, the number of atoms remaining is halved. Initially, there are twice as many atoms of isotope $\mathrm{A}$ as of isotope $\mathrm{B}$, and after 24 minutes there are the same number of atoms of each isotope. How long does it take the number of atoms of isotope B to halve?	[ "8" ]
Solve the system of equations: $$ \begin{aligned} & \log _{10}\left(x^{3}\right)+\log _{10}\left(y^{2}\right)=11 \\ & \log _{10}\left(x^{2}\right)-\log _{10}\left(y^{3}\right)=3 \end{aligned} $$	[ "$10^{3},10$" ]
A positive integer $n$ is called "savage" if the integers $\{1,2,\dots,n\}$ can be partitioned into three sets $A, B$ and $C$ such that i) the sum of the elements in each of $A, B$, and $C$ is the same, ii) $A$ contains only odd numbers, iii) $B$ contains only even numbers, and iv) C contains every multiple of 3 (and possibly other numbers). Determine all even savage integers less than 100.	[ "8,32,44,68,80" ]
Tanner has two identical dice. Each die has six faces which are numbered 2, 3, 5, $7,11,13$. When Tanner rolls the two dice, what is the probability that the sum of the numbers on the top faces is a prime number?	[ "$\\frac{1}{6}$" ]
If $\frac{1}{\cos x}-\tan x=3$, what is the numerical value of $\sin x$ ?	[ "$-\\frac{4}{5}$" ]
Determine all linear functions $f(x)=a x+b$ such that if $g(x)=f^{-1}(x)$ for all values of $x$, then $f(x)-g(x)=44$ for all values of $x$. (Note: $f^{-1}$ is the inverse function of $f$.)	[ "$f(x)=x+22$" ]
Determine all pairs $(a, b)$ of positive integers for which $a^{3}+2 a b=2013$.	[ "$(1,1006),(3,331),(11,31)$" ]
Determine all real values of $x$ for which $\log _{2}\left(2^{x-1}+3^{x+1}\right)=2 x-\log _{2}\left(3^{x}\right)$.	[ "$\\frac{\\log 2}{\\log 2-\\log 3}$" ]
A multiplicative partition of a positive integer $n \geq 2$ is a way of writing $n$ as a product of one or more integers, each greater than 1. Note that we consider a positive integer to be a multiplicative partition of itself. Also, the order of the factors in a partition does not matter; for example, $2 \times 3 \times 5$ and $2 \times 5 \times 3$ are considered to be the same partition of 30 . For each positive integer $n \geq 2$, define $P(n)$ to be the number of multiplicative partitions of $n$. We also define $P(1)=1$. Note that $P(40)=7$, since the multiplicative partitions of 40 are $40,2 \times 20,4 \times 10$, $5 \times 8,2 \times 2 \times 10,2 \times 4 \times 5$, and $2 \times 2 \times 2 \times 5$. (In each part, we use "partition" to mean "multiplicative partition". We also call the numbers being multiplied together in a given partition the "parts" of the partition.) Determine the value of $P(64)$.	[ "11" ]
A multiplicative partition of a positive integer $n \geq 2$ is a way of writing $n$ as a product of one or more integers, each greater than 1. Note that we consider a positive integer to be a multiplicative partition of itself. Also, the order of the factors in a partition does not matter; for example, $2 \times 3 \times 5$ and $2 \times 5 \times 3$ are considered to be the same partition of 30 . For each positive integer $n \geq 2$, define $P(n)$ to be the number of multiplicative partitions of $n$. We also define $P(1)=1$. Note that $P(40)=7$, since the multiplicative partitions of 40 are $40,2 \times 20,4 \times 10$, $5 \times 8,2 \times 2 \times 10,2 \times 4 \times 5$, and $2 \times 2 \times 2 \times 5$. (In each part, we use "partition" to mean "multiplicative partition". We also call the numbers being multiplied together in a given partition the "parts" of the partition.) Determine the value of $P(1000)$.	[ "31" ]
What are all values of $x$ such that $$ \log _{5}(x+3)+\log _{5}(x-1)=1 ? $$	[ "2" ]
A chef aboard a luxury liner wants to cook a goose. The time $t$ in hours to cook a goose at $180^{\circ} \mathrm{C}$ depends on the mass of the goose $m$ in kilograms according to the formula $$ t=a m^{b} $$ where $a$ and $b$ are constants. The table below gives the times observed to cook a goose at $180^{\circ} \mathrm{C}$. \| Mass, $m(\mathrm{~kg})$ \| Time, $t(\mathrm{~h})$ \| \| :---: \| :---: \| \| 3.00 \| 2.75 \| \| 6.00 \| 3.75 \| Using the data in the table, determine both $a$ and $b$ to two decimal places.	[ "$1.68,0.45$" ]
A circle passes through the origin and the points of intersection of the parabolas $y=x^{2}-3$ and $y=-x^{2}-2 x+9$. Determine the coordinates of the centre of this circle.	[ "$(-\\frac{1}{2}, \\frac{7}{2})$" ]
In a soccer league with 5 teams, each team plays 20 games(that is, 5 games with each of the other 4 teams). For each team, every game ends in a win (W), a loss (L), or a tie (T). The numbers of wins, losses and ties for each team at the end of the season are shown in the table. Determine the values of $x, y$ and $z$. \| Team \| W \| L \| T \| \| :---: \| ---: \| ---: \| ---: \| \| A \| 2 \| 15 \| 3 \| \| B \| 7 \| 9 \| 4 \| \| C \| 6 \| 12 \| 2 \| \| D \| 10 \| 8 \| 2 \| \| E \| $x$ \| $y$ \| $z$ \|	[ "19,0,1" ]
Three thin metal rods of lengths 9,12 and 15 are welded together to form a right-angled triangle, which is held in a horizontal position. A solid sphere of radius 5 rests in the triangle so that it is tangent to each of the three sides. Assuming that the thickness of the rods can be neglected, how high above the plane of the triangle is the top of the sphere?	[ "5" ]
Triangle $A B C$ has vertices $A(0,5), B(3,0)$ and $C(8,3)$. Determine the measure of $\angle A C B$.	[ "$45^{\\circ}$" ]
Blaise and Pierre will play 6 games of squash. Since they are equally skilled, each is equally likely to win any given game. (In squash, there are no ties.) The probability that each of them will win 3 of the 6 games is $\frac{5}{16}$. What is the probability that Blaise will win more games than Pierre?	[ "$\\frac{11}{32}$" ]
Determine all real values of $x$ for which $$ 3^{x+2}+2^{x+2}+2^{x}=2^{x+5}+3^{x} $$	[ "3" ]
Determine all real values of $x$ such that $$ \log _{5 x+9}\left(x^{2}+6 x+9\right)+\log _{x+3}\left(5 x^{2}+24 x+27\right)=4 $$	[ "$0,-1,-\\frac{3}{2}$" ]
For each positive integer $N$, an Eden sequence from $\{1,2,3, \ldots, N\}$ is defined to be a sequence that satisfies the following conditions: (i) each of its terms is an element of the set of consecutive integers $\{1,2,3, \ldots, N\}$, (ii) the sequence is increasing, and (iii) the terms in odd numbered positions are odd and the terms in even numbered positions are even. For example, the four Eden sequences from $\{1,2,3\}$ are $$ \begin{array}{llll} 1 & 3 & 1,2 & 1,2,3 \end{array} $$ Determine the number of Eden sequences from $\{1,2,3,4,5\}$.	[ "12" ]
For each positive integer $N$, an Eden sequence from $\{1,2,3, \ldots, N\}$ is defined to be a sequence that satisfies the following conditions: (i) each of its terms is an element of the set of consecutive integers $\{1,2,3, \ldots, N\}$, (ii) the sequence is increasing, and (iii) the terms in odd numbered positions are odd and the terms in even numbered positions are even. For example, the four Eden sequences from $\{1,2,3\}$ are $$ \begin{array}{llll} 1 & 3 & 1,2 & 1,2,3 \end{array} $$ For each positive integer $N$, define $e(N)$ to be the number of Eden sequences from $\{1,2,3, \ldots, N\}$. If $e(17)=4180$ and $e(20)=17710$, determine $e(18)$ and $e(19)$.	[ "$6764$,$10945$" ]
If $a$ is chosen randomly from the set $\{1,2,3,4,5\}$ and $b$ is chosen randomly from the set $\{6,7,8\}$, what is the probability that $a^{b}$ is an even number?	[ "$\\frac{2}{5}$" ]
A bag contains some blue and some green hats. On each turn, Julia removes one hat without looking, with each hat in the bag being equally likely to be chosen. If it is green, she adds a blue hat into the bag from her supply of extra hats, and if it is blue, she adds a green hat to the bag. The bag initially contains 4 blue hats and 2 green hats. What is the probability that the bag again contains 4 blue hats and 2 green hats after two turns?	[ "$\\frac{11}{18}$" ]
Suppose that, for some angles $x$ and $y$, $$ \begin{aligned} & \sin ^{2} x+\cos ^{2} y=\frac{3}{2} a \\ & \cos ^{2} x+\sin ^{2} y=\frac{1}{2} a^{2} \end{aligned} $$ Determine the possible value(s) of $a$.	[ "1" ]
The sequence $2,5,10,50,500, \ldots$ is formed so that each term after the second is the product of the two previous terms. The 15 th term ends with exactly $k$ zeroes. What is the value of $k$ ?	[ "233" ]
If $\log _{2} x-2 \log _{2} y=2$, determine $y$, as a function of $x$	[ "$\\frac{1}{2},\\sqrt{x}$" ]
Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. Determine all real numbers $k$ for which $f(x)$ is constant for all values of $x$.	[ "$-\\frac{3}{2}$" ]
Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. If $k=-0.7$, determine all solutions to the equation $f(x)=0$.	[ "$x=\\frac{1}{6} \\pi+\\pi k, \\frac{1}{3} \\pi+\\pi k, \\frac{2}{3} \\pi+\\pi k, \\frac{5}{6} \\pi+\\pi k$" ]
Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. Determine all real numbers $k$ for which there exists a real number $c$ such that $f(c)=0$.	[ "$[-1,-\\frac{1}{2}]$" ]
Hexagon $A B C D E F$ has vertices $A(0,0), B(4,0), C(7,2), D(7,5), E(3,5)$, $F(0,3)$. What is the area of hexagon $A B C D E F$ ?	[ "29" ]
A list $a_{1}, a_{2}, a_{3}, a_{4}$ of rational numbers is defined so that if one term is equal to $r$, then the next term is equal to $1+\frac{1}{1+r}$. For example, if $a_{3}=\frac{41}{29}$, then $a_{4}=1+\frac{1}{1+(41 / 29)}=\frac{99}{70}$. If $a_{3}=\frac{41}{29}$, what is the value of $a_{1} ?$	[ "$\\frac{7}{5}$" ]
A hollow cylindrical tube has a radius of $10 \mathrm{~mm}$ and a height of $100 \mathrm{~mm}$. The tube sits flat on one of its circular faces on a horizontal table. The tube is filled with water to a depth of $h \mathrm{~mm}$. A solid cylindrical rod has a radius of $2.5 \mathrm{~mm}$ and a height of $150 \mathrm{~mm}$. The rod is inserted into the tube so that one of its circular faces sits flat on the bottom of the tube. The height of the water in the tube is now $64 \mathrm{~mm}$. Determine the value of $h$.	[ "60" ]
A function $f$ has the property that $f\left(\frac{2 x+1}{x}\right)=x+6$ for all real values of $x \neq 0$. What is the value of $f(4) ?$	[ "$\\frac{13}{2}$" ]
Determine all real numbers $a, b$ and $c$ for which the graph of the function $y=\log _{a}(x+b)+c$ passes through the points $P(3,5), Q(5,4)$ and $R(11,3)$.	[ "$\\frac{1}{3},-2,5$" ]
A computer is programmed to choose an integer between 1 and 99, inclusive, so that the probability that it selects the integer $x$ is equal to $\log _{100}\left(1+\frac{1}{x}\right)$. Suppose that the probability that $81 \leq x \leq 99$ is equal to 2 times the probability that $x=n$ for some integer $n$. What is the value of $n$ ?	[ "9" ]
What is the smallest positive integer $x$ for which $\frac{1}{32}=\frac{x}{10^{y}}$ for some positive integer $y$ ?	[ "3125" ]
Determine all possible values for the area of a right-angled triangle with one side length equal to 60 and with the property that its side lengths form an arithmetic sequence. (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, $3,5,7,9$ are the first four terms of an arithmetic sequence.)	[ "2400, 1350, 864" ]
Amrita and Zhang cross a lake in a straight line with the help of a one-seat kayak. Each can paddle the kayak at $7 \mathrm{~km} / \mathrm{h}$ and swim at $2 \mathrm{~km} / \mathrm{h}$. They start from the same point at the same time with Amrita paddling and Zhang swimming. After a while, Amrita stops the kayak and immediately starts swimming. Upon reaching the kayak (which has not moved since Amrita started swimming), Zhang gets in and immediately starts paddling. They arrive on the far side of the lake at the same time, 90 minutes after they began. Determine the amount of time during these 90 minutes that the kayak was not being paddled.	[ "50" ]
Determine all pairs $(x, y)$ of real numbers that satisfy the system of equations $$ \begin{aligned} x\left(\frac{1}{2}+y-2 x^{2}\right) & =0 \\ y\left(\frac{5}{2}+x-y\right) & =0 \end{aligned} $$	[ "$(0,0),(0, \\frac{5}{2}),(\\frac{1}{2}, 0),(-\\frac{1}{2}, 0),(\\frac{3}{2}, 4),(-1, \\frac{3}{2})$" ]
Determine all real numbers $x>0$ for which $$ \log _{4} x-\log _{x} 16=\frac{7}{6}-\log _{x} 8 $$	[ "$2^{-2 / 3}$, $8$" ]
The string $A A A B B B A A B B$ is a string of ten letters, each of which is $A$ or $B$, that does not include the consecutive letters $A B B A$. The string $A A A B B A A A B B$ is a string of ten letters, each of which is $A$ or $B$, that does include the consecutive letters $A B B A$. Determine, with justification, the total number of strings of ten letters, each of which is $A$ or $B$, that do not include the consecutive letters $A B B A$.	[ "631" ]
Let $k$ be a positive integer with $k \geq 2$. Two bags each contain $k$ balls, labelled with the positive integers from 1 to $k$. André removes one ball from each bag. (In each bag, each ball is equally likely to be chosen.) Define $P(k)$ to be the probability that the product of the numbers on the two balls that he chooses is divisible by $k$. Calculate $P(10)$.	[ "$\\frac{27}{100}$" ]
In an arithmetic sequence, the first term is 1 and the last term is 19 . The sum of all the terms in the sequence is 70 . How many terms does the sequence have? (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, 3, 5, 7, 9 is an arithmetic sequence with four terms.)	[ "7" ]
Suppose that $a(x+b(x+3))=2(x+6)$ for all values of $x$. Determine $a$ and $b$.	[ "-2,-2" ]
An integer $n$, with $100 \leq n \leq 999$, is chosen at random. What is the probability that the sum of the digits of $n$ is 24 ?	[ "$\\frac{1}{90}$" ]
The parabola $y=x^{2}-2 x+4$ is translated $p$ units to the right and $q$ units down. The $x$-intercepts of the resulting parabola are 3 and 5 . What are the values of $p$ and $q$ ?	[ "3,4" ]
If $\log _{2} x,\left(1+\log _{4} x\right)$, and $\log _{8} 4 x$ are consecutive terms of a geometric sequence, determine the possible values of $x$. (A geometric sequence is a sequence in which each term after the first is obtained from the previous term by multiplying it by a constant. For example, $3,6,12$ is a geometric sequence with three terms.)	[ "$64,\\frac{1}{4}$" ]
Determine the two pairs of positive integers $(a, b)$ with $a<b$ that satisfy the equation $\sqrt{a}+\sqrt{b}=\sqrt{50}$.	[ "(2,32), (8,18)" ]
Consider the system of equations: $$ \begin{aligned} c+d & =2000 \\ \frac{c}{d} & =k \end{aligned} $$ Determine the number of integers $k$ with $k \geq 0$ for which there is at least one pair of integers $(c, d)$ that is a solution to the system.	[ "20" ]
Determine all real numbers $x$ for which $2 \log _{2}(x-1)=1-\log _{2}(x+2)$.	[ "$\\sqrt{3}$" ]
Consider the function $f(x)=x^{2}-2 x$. Determine all real numbers $x$ that satisfy the equation $f(f(f(x)))=3$.	[ "$3,1,-1,1+\\sqrt{2}, 1-\\sqrt{2}$" ]
Suppose that $x$ satisfies $0<x<\frac{\pi}{2}$ and $\cos \left(\frac{3}{2} \cos x\right)=\sin \left(\frac{3}{2} \sin x\right)$. Determine all possible values of $\sin 2 x$, expressing your answers in the form $\frac{a \pi^{2}+b \pi+c}{d}$ where $a, b, c, d$ are integers.	[ "$\\frac{\\pi^{2}-9}{9}$" ]
For positive integers $a$ and $b$, define $f(a, b)=\frac{a}{b}+\frac{b}{a}+\frac{1}{a b}$. For example, the value of $f(1,2)$ is 3 . Determine the value of $f(2,5)$.	[ "3" ]
For positive integers $a$ and $b$, define $f(a, b)=\frac{a}{b}+\frac{b}{a}+\frac{1}{a b}$. For example, the value of $f(1,2)$ is 3 . Determine all positive integers $a$ for which $f(a, a)$ is an integer.	[ "1" ]
Amir and Brigitte play a card game. Amir starts with a hand of 6 cards: 2 red, 2 yellow and 2 green. Brigitte starts with a hand of 4 cards: 2 purple and 2 white. Amir plays first. Amir and Brigitte alternate turns. On each turn, the current player chooses one of their own cards at random and places it on the table. The cards remain on the table for the rest of the game. A player wins and the game ends when they have placed two cards of the same colour on the table. Determine the probability that Amir wins the game.	[ "$\\frac{7}{15}$" ]
Consider the sequence $t_{1}=1, t_{2}=-1$ and $t_{n}=\left(\frac{n-3}{n-1}\right) t_{n-2}$ where $n \geq 3$. What is the value of $t_{1998}$ ?	[ "$\\frac{-1}{1997}$" ]
The $n$th term of an arithmetic sequence is given by $t_{n}=555-7 n$. If $S_{n}=t_{1}+t_{2}+\ldots+t_{n}$, determine the smallest value of $n$ for which $S_{n}<0$.	[ "158" ]
If $x$ and $y$ are real numbers, determine all solutions $(x, y)$ of the system of equations $$ \begin{aligned} & x^{2}-x y+8=0 \\ & x^{2}-8 x+y=0 \end{aligned} $$	[ "$(-1,-9),(4+2 \\sqrt{2}, 8),(4-2 \\sqrt{2}, 8)$" ]
The equations $x^{2}+5 x+6=0$ and $x^{2}+5 x-6=0$ each have integer solutions whereas only one of the equations in the pair $x^{2}+4 x+5=0$ and $x^{2}+4 x-5=0$ has integer solutions. Determine $q$ in terms of $a$ and $b$.	[ "$\\frac{a b}{2}$" ]
Determine all values of $k$, with $k \neq 0$, for which the parabola $$ y=k x^{2}+(5 k+3) x+(6 k+5) $$ has its vertex on the $x$-axis.	[ "$-1,-9$" ]
The function $f(x)$ satisfies the equation $f(x)=f(x-1)+f(x+1)$ for all values of $x$. If $f(1)=1$ and $f(2)=3$, what is the value of $f(2008)$ ?	[ "-1" ]
The numbers $a, b, c$, in that order, form a three term arithmetic sequence (see below) and $a+b+c=60$. The numbers $a-2, b, c+3$, in that order, form a three term geometric sequence. Determine all possible values of $a, b$ and $c$. (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, $3,5,7$ is an arithmetic sequence with three terms. A geometric sequence is a sequence in which each term after the first is obtained from the previous term by multiplying it by a constant. For example, $3,6,12$ is a geometric sequence with three terms.) Present your answer in the form of coordinates (e.g. (1, 2, 3) for a=1, b=2, c=3).	[ "$(27,20,13), (18,20,22)$" ]
The average of three consecutive multiples of 3 is $a$. The average of four consecutive multiples of 4 is $a+27$. The average of the smallest and largest of these seven integers is 42 . Determine the value of $a$.	[ "27" ]
Billy and Crystal each have a bag of 9 balls. The balls in each bag are numbered from 1 to 9. Billy and Crystal each remove one ball from their own bag. Let $b$ be the sum of the numbers on the balls remaining in Billy's bag. Let $c$ be the sum of the numbers on the balls remaining in Crystal's bag. Determine the probability that $b$ and $c$ differ by a multiple of 4 .	[ "$\\frac{7}{27}$" ]
The equation $2^{x+2} 5^{6-x}=10^{x^{2}}$ has two real solutions. Determine these two solutions.	[ "$2,-\\log _{10} 250$" ]
Determine all real solutions to the system of equations $$ \begin{aligned} & x+\log _{10} x=y-1 \\ & y+\log _{10}(y-1)=z-1 \\ & z+\log _{10}(z-2)=x+2 \end{aligned} $$ and prove that there are no more solutions.	[ "$1,2,3$" ]
The positive integers 34 and 80 have exactly two positive common divisors, namely 1 and 2. How many positive integers $n$ with $1 \leq n \leq 30$ have the property that $n$ and 80 have exactly two positive common divisors?	[ "9" ]
A function $f$ is defined so that - $f(1)=1$, - if $n$ is an even positive integer, then $f(n)=f\left(\frac{1}{2} n\right)$, and - if $n$ is an odd positive integer with $n>1$, then $f(n)=f(n-1)+1$. For example, $f(34)=f(17)$ and $f(17)=f(16)+1$. Determine the value of $f(50)$.	[ "3" ]
The perimeter of equilateral $\triangle P Q R$ is 12. The perimeter of regular hexagon $S T U V W X$ is also 12. What is the ratio of the area of $\triangle P Q R$ to the area of $S T U V W X$ ?	[ "$\\frac{2}{3}$" ]
For how many integers $k$ with $0<k<18$ is $\frac{5 \sin \left(10 k^{\circ}\right)-2}{\sin ^{2}\left(10 k^{\circ}\right)} \geq 2$ ?	[ "13" ]
Eight people, including triplets Barry, Carrie and Mary, are going for a trip in four canoes. Each canoe seats two people. The eight people are to be randomly assigned to the four canoes in pairs. What is the probability that no two of Barry, Carrie and Mary will be in the same canoe?	[ "$\\frac{4}{7}$" ]
Diagonal $W Y$ of square $W X Y Z$ has slope 2. Determine the sum of the slopes of $W X$ and $X Y$.	[ "$-\\frac{8}{3}$" ]
Determine all values of $x$ such that $\log _{2 x}(48 \sqrt[3]{3})=\log _{3 x}(162 \sqrt[3]{2})$.	[ "$\\sqrt{6}$" ]
In an infinite array with two rows, the numbers in the top row are denoted $\ldots, A_{-2}, A_{-1}, A_{0}, A_{1}, A_{2}, \ldots$ and the numbers in the bottom row are denoted $\ldots, B_{-2}, B_{-1}, B_{0}, B_{1}, B_{2}, \ldots$ For each integer $k$, the entry $A_{k}$ is directly above the entry $B_{k}$ in the array, as shown: \| $\ldots$ \| $A_{-2}$ \| $A_{-1}$ \| $A_{0}$ \| $A_{1}$ \| $A_{2}$ \| $\ldots$ \| \| :--- \| :--- \| :--- \| :--- \| :--- \| :--- \| :--- \| \| $\ldots$ \| $B_{-2}$ \| $B_{-1}$ \| $B_{0}$ \| $B_{1}$ \| $B_{2}$ \| $\ldots$ \| For each integer $k, A_{k}$ is the average of the entry to its left, the entry to its right, and the entry below it; similarly, each entry $B_{k}$ is the average of the entry to its left, the entry to its right, and the entry above it. In one such array, $A_{0}=A_{1}=A_{2}=0$ and $A_{3}=1$. Determine the value of $A_{4}$.	[ "6" ]
The populations of Alphaville and Betaville were equal at the end of 1995. The population of Alphaville decreased by $2.9 \%$ during 1996, then increased by $8.9 \%$ during 1997 , and then increased by $6.9 \%$ during 1998 . The population of Betaville increased by $r \%$ in each of the three years. If the populations of the towns are equal at the end of 1998, determine the value of $r$ correct to one decimal place.	[ "4.2" ]
Determine the coordinates of the points of intersection of the graphs of $y=\log _{10}(x-2)$ and $y=1-\log _{10}(x+1)$.	[ "$(4, \\log _{10} 2)$" ]
Charlie was born in the twentieth century. On his birthday in the present year (2014), he notices that his current age is twice the number formed by the rightmost two digits of the year in which he was born. Compute the four-digit year in which Charlie was born.	[ "1938" ]
Let $A, B$, and $C$ be randomly chosen (not necessarily distinct) integers between 0 and 4 inclusive. Pat and Chris compute the value of $A+B \cdot C$ by two different methods. Pat follows the proper order of operations, computing $A+(B \cdot C)$. Chris ignores order of operations, choosing instead to compute $(A+B) \cdot C$. Compute the probability that Pat and Chris get the same answer.	[ "$\\frac{9}{25}$" ]
Bobby, Peter, Greg, Cindy, Jan, and Marcia line up for ice cream. In an acceptable lineup, Greg is ahead of Peter, Peter is ahead of Bobby, Marcia is ahead of Jan, and Jan is ahead of Cindy. For example, the lineup with Greg in front, followed by Peter, Marcia, Jan, Cindy, and Bobby, in that order, is an acceptable lineup. Compute the number of acceptable lineups.	[ "20" ]
In triangle $A B C, a=12, b=17$, and $c=13$. Compute $b \cos C-c \cos B$.	[ "10" ]
The sequence of words $\left\{a_{n}\right\}$ is defined as follows: $a_{1}=X, a_{2}=O$, and for $n \geq 3, a_{n}$ is $a_{n-1}$ followed by the reverse of $a_{n-2}$. For example, $a_{3}=O X, a_{4}=O X O, a_{5}=O X O X O$, and $a_{6}=O X O X O O X O$. Compute the number of palindromes in the first 1000 terms of this sequence.	[ "667" ]
Compute the smallest positive integer $n$ such that $214 \cdot n$ and $2014 \cdot n$ have the same number of divisors.	[ "19133" ]
Let $N$ be the least integer greater than 20 that is a palindrome in both base 20 and base 14 . For example, the three-digit base-14 numeral (13)5(13) ${ }_{14}$ (representing $13 \cdot 14^{2}+5 \cdot 14^{1}+13 \cdot 14^{0}$ ) is a palindrome in base 14 , but not in base 20 , and the three-digit base-14 numeral (13)31 14 is not a palindrome in base 14 . Compute the base-10 representation of $N$.	[ "105" ]
$\quad$ Compute the greatest integer $k \leq 1000$ such that $\left(\begin{array}{c}1000 \\ k\end{array}\right)$ is a multiple of 7 .	[ "979" ]
An integer-valued function $f$ is called tenuous if $f(x)+f(y)>x^{2}$ for all positive integers $x$ and $y$. Let $g$ be a tenuous function such that $g(1)+g(2)+\cdots+g(20)$ is as small as possible. Compute the minimum possible value for $g(14)$.	[ "136" ]

Dan was born in a year between 1300 and 1400. Steve was born in a year between 1400 and 1500. Each was born on April 6 in a year that is a perfect square. Each lived for 110 years. In what year while they were both alive were their ages both perfect squares on April 7?

[ "1469" ]

Determine all values of $k$ for which the points $A(1,2), B(11,2)$ and $C(k, 6)$ form a right-angled triangle.

[ "1,3,9,11" ]

If $\cos \theta=\tan \theta$, determine all possible values of $\sin \theta$, giving your answer(s) as simplified exact numbers.

[ "$\\frac{-1+\\sqrt{5}}{2}$" ]

Linh is driving at $60 \mathrm{~km} / \mathrm{h}$ on a long straight highway parallel to a train track. Every 10 minutes, she is passed by a train travelling in the same direction as she is. These trains depart from the station behind her every 3 minutes and all travel at the same constant speed. What is the constant speed of the trains, in $\mathrm{km} / \mathrm{h}$ ?

[ "$\\frac{600}{7}$" ]

Determine all pairs $(a, b)$ of real numbers that satisfy the following system of equations: $$ \begin{aligned} \sqrt{a}+\sqrt{b} & =8 \\ \log _{10} a+\log _{10} b & =2 \end{aligned} $$ Give your answer(s) as pairs of simplified exact numbers.

[ "$(22+8 \\sqrt{6}, 22-8 \\sqrt{6})$,$(22-8 \\sqrt{6}, 22+8 \\sqrt{6})$" ]

A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ \left|a_{1}-a_{2}\right|+\left|a_{3}-a_{4}\right| $$ over all permutations $a_{1}, a_{2}, a_{3}, a_{4}$ of $1,2,3,4$.

[ "$\\frac{10}{3}$" ]

A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ a_{1}-a_{2}+a_{3}-a_{4}+a_{5}-a_{6}+a_{7} $$ over all permutations $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}, a_{7}$ of $1,2,3,4,5,6,7$.

[ "4" ]

A permutation of a list of numbers is an ordered arrangement of the numbers in that list. For example, $3,2,4,1,6,5$ is a permutation of $1,2,3,4,5,6$. We can write this permutation as $a_{1}, a_{2}, a_{3}, a_{4}, a_{5}, a_{6}$, where $a_{1}=3, a_{2}=2, a_{3}=4, a_{4}=1, a_{5}=6$, and $a_{6}=5$. Determine the average value of $$ \left|a_{1}-a_{2}\right|+\left|a_{3}-a_{4}\right|+\cdots+\left|a_{197}-a_{198}\right|+\left|a_{199}-a_{200}\right| $$ over all permutations $a_{1}, a_{2}, a_{3}, \ldots, a_{199}, a_{200}$ of $1,2,3,4, \ldots, 199,200$. (The sum labelled (*) contains 100 terms of the form $\left|a_{2 k-1}-a_{2 k}\right|$.)

[ "6700" ]

If $0^{\circ}<x<90^{\circ}$ and $3 \sin (x)-\cos \left(15^{\circ}\right)=0$, what is the value of $x$ to the nearest tenth of a degree?

[ "$18.8^{\\circ}$" ]

The function $f(x)$ has the property that $f(2 x+3)=2 f(x)+3$ for all $x$. If $f(0)=6$, what is the value of $f(9)$ ?

[ "33" ]

Suppose that the functions $f(x)$ and $g(x)$ satisfy the system of equations $$ \begin{aligned} f(x)+3 g(x) & =x^{2}+x+6 \\ 2 f(x)+4 g(x) & =2 x^{2}+4 \end{aligned} $$ for all $x$. Determine the values of $x$ for which $f(x)=g(x)$.

[ "$5,-2$" ]

In a short-track speed skating event, there are five finalists including two Canadians. The first three skaters to finish the race win a medal. If all finalists have the same chance of finishing in any position, what is the probability that neither Canadian wins a medal?

[ "$\\frac{1}{10}$" ]

Determine the number of positive integers less than or equal to 300 that are multiples of 3 or 5 , but are not multiples of 10 or 15 .

[ "100" ]

In the series of odd numbers $1+3+5-7-9-11+13+15+17-19-21-23 \ldots$ the signs alternate every three terms, as shown. What is the sum of the first 300 terms of the series?

[ "-900" ]

A two-digit number has the property that the square of its tens digit plus ten times its units digit equals the square of its units digit plus ten times its tens digit. Determine all two-digit numbers which have this property, and are prime numbers.

[ "11,19,37,73" ]

A lead box contains samples of two radioactive isotopes of iron. Isotope A decays so that after every 6 minutes, the number of atoms remaining is halved. Initially, there are twice as many atoms of isotope $\mathrm{A}$ as of isotope $\mathrm{B}$, and after 24 minutes there are the same number of atoms of each isotope. How long does it take the number of atoms of isotope B to halve?

[ "8" ]

Solve the system of equations: $$ \begin{aligned} & \log _{10}\left(x^{3}\right)+\log _{10}\left(y^{2}\right)=11 \\ & \log _{10}\left(x^{2}\right)-\log _{10}\left(y^{3}\right)=3 \end{aligned} $$

[ "$10^{3},10$" ]

A positive integer $n$ is called "savage" if the integers $\{1,2,\dots,n\}$ can be partitioned into three sets $A, B$ and $C$ such that i) the sum of the elements in each of $A, B$, and $C$ is the same, ii) $A$ contains only odd numbers, iii) $B$ contains only even numbers, and iv) C contains every multiple of 3 (and possibly other numbers). Determine all even savage integers less than 100.

[ "8,32,44,68,80" ]

Tanner has two identical dice. Each die has six faces which are numbered 2, 3, 5, $7,11,13$. When Tanner rolls the two dice, what is the probability that the sum of the numbers on the top faces is a prime number?

[ "$\\frac{1}{6}$" ]

If $\frac{1}{\cos x}-\tan x=3$, what is the numerical value of $\sin x$ ?

[ "$-\\frac{4}{5}$" ]

Determine all linear functions $f(x)=a x+b$ such that if $g(x)=f^{-1}(x)$ for all values of $x$, then $f(x)-g(x)=44$ for all values of $x$. (Note: $f^{-1}$ is the inverse function of $f$.)

[ "$f(x)=x+22$" ]

Determine all pairs $(a, b)$ of positive integers for which $a^{3}+2 a b=2013$.

[ "$(1,1006),(3,331),(11,31)$" ]

Determine all real values of $x$ for which $\log _{2}\left(2^{x-1}+3^{x+1}\right)=2 x-\log _{2}\left(3^{x}\right)$.

[ "$\\frac{\\log 2}{\\log 2-\\log 3}$" ]

A multiplicative partition of a positive integer $n \geq 2$ is a way of writing $n$ as a product of one or more integers, each greater than 1. Note that we consider a positive integer to be a multiplicative partition of itself. Also, the order of the factors in a partition does not matter; for example, $2 \times 3 \times 5$ and $2 \times 5 \times 3$ are considered to be the same partition of 30 . For each positive integer $n \geq 2$, define $P(n)$ to be the number of multiplicative partitions of $n$. We also define $P(1)=1$. Note that $P(40)=7$, since the multiplicative partitions of 40 are $40,2 \times 20,4 \times 10$, $5 \times 8,2 \times 2 \times 10,2 \times 4 \times 5$, and $2 \times 2 \times 2 \times 5$. (In each part, we use "partition" to mean "multiplicative partition". We also call the numbers being multiplied together in a given partition the "parts" of the partition.) Determine the value of $P(64)$.

[ "11" ]

A multiplicative partition of a positive integer $n \geq 2$ is a way of writing $n$ as a product of one or more integers, each greater than 1. Note that we consider a positive integer to be a multiplicative partition of itself. Also, the order of the factors in a partition does not matter; for example, $2 \times 3 \times 5$ and $2 \times 5 \times 3$ are considered to be the same partition of 30 . For each positive integer $n \geq 2$, define $P(n)$ to be the number of multiplicative partitions of $n$. We also define $P(1)=1$. Note that $P(40)=7$, since the multiplicative partitions of 40 are $40,2 \times 20,4 \times 10$, $5 \times 8,2 \times 2 \times 10,2 \times 4 \times 5$, and $2 \times 2 \times 2 \times 5$. (In each part, we use "partition" to mean "multiplicative partition". We also call the numbers being multiplied together in a given partition the "parts" of the partition.) Determine the value of $P(1000)$.

[ "31" ]

What are all values of $x$ such that $$ \log _{5}(x+3)+\log _{5}(x-1)=1 ? $$

[ "2" ]

A chef aboard a luxury liner wants to cook a goose. The time $t$ in hours to cook a goose at $180^{\circ} \mathrm{C}$ depends on the mass of the goose $m$ in kilograms according to the formula $$ t=a m^{b} $$ where $a$ and $b$ are constants. The table below gives the times observed to cook a goose at $180^{\circ} \mathrm{C}$. | Mass, $m(\mathrm{~kg})$ | Time, $t(\mathrm{~h})$ | | :---: | :---: | | 3.00 | 2.75 | | 6.00 | 3.75 | Using the data in the table, determine both $a$ and $b$ to two decimal places.

[ "$1.68,0.45$" ]

A circle passes through the origin and the points of intersection of the parabolas $y=x^{2}-3$ and $y=-x^{2}-2 x+9$. Determine the coordinates of the centre of this circle.

[ "$(-\\frac{1}{2}, \\frac{7}{2})$" ]

In a soccer league with 5 teams, each team plays 20 games(that is, 5 games with each of the other 4 teams). For each team, every game ends in a win (W), a loss (L), or a tie (T). The numbers of wins, losses and ties for each team at the end of the season are shown in the table. Determine the values of $x, y$ and $z$. | Team | W | L | T | | :---: | ---: | ---: | ---: | | A | 2 | 15 | 3 | | B | 7 | 9 | 4 | | C | 6 | 12 | 2 | | D | 10 | 8 | 2 | | E | $x$ | $y$ | $z$ |

[ "19,0,1" ]

Three thin metal rods of lengths 9,12 and 15 are welded together to form a right-angled triangle, which is held in a horizontal position. A solid sphere of radius 5 rests in the triangle so that it is tangent to each of the three sides. Assuming that the thickness of the rods can be neglected, how high above the plane of the triangle is the top of the sphere?

[ "5" ]

Triangle $A B C$ has vertices $A(0,5), B(3,0)$ and $C(8,3)$. Determine the measure of $\angle A C B$.

[ "$45^{\\circ}$" ]

Blaise and Pierre will play 6 games of squash. Since they are equally skilled, each is equally likely to win any given game. (In squash, there are no ties.) The probability that each of them will win 3 of the 6 games is $\frac{5}{16}$. What is the probability that Blaise will win more games than Pierre?

[ "$\\frac{11}{32}$" ]

Determine all real values of $x$ for which $$ 3^{x+2}+2^{x+2}+2^{x}=2^{x+5}+3^{x} $$

[ "3" ]

Determine all real values of $x$ such that $$ \log _{5 x+9}\left(x^{2}+6 x+9\right)+\log _{x+3}\left(5 x^{2}+24 x+27\right)=4 $$

[ "$0,-1,-\\frac{3}{2}$" ]

For each positive integer $N$, an Eden sequence from $\{1,2,3, \ldots, N\}$ is defined to be a sequence that satisfies the following conditions: (i) each of its terms is an element of the set of consecutive integers $\{1,2,3, \ldots, N\}$, (ii) the sequence is increasing, and (iii) the terms in odd numbered positions are odd and the terms in even numbered positions are even. For example, the four Eden sequences from $\{1,2,3\}$ are $$ \begin{array}{llll} 1 & 3 & 1,2 & 1,2,3 \end{array} $$ Determine the number of Eden sequences from $\{1,2,3,4,5\}$.

[ "12" ]

For each positive integer $N$, an Eden sequence from $\{1,2,3, \ldots, N\}$ is defined to be a sequence that satisfies the following conditions: (i) each of its terms is an element of the set of consecutive integers $\{1,2,3, \ldots, N\}$, (ii) the sequence is increasing, and (iii) the terms in odd numbered positions are odd and the terms in even numbered positions are even. For example, the four Eden sequences from $\{1,2,3\}$ are $$ \begin{array}{llll} 1 & 3 & 1,2 & 1,2,3 \end{array} $$ For each positive integer $N$, define $e(N)$ to be the number of Eden sequences from $\{1,2,3, \ldots, N\}$. If $e(17)=4180$ and $e(20)=17710$, determine $e(18)$ and $e(19)$.

[ "$6764$,$10945$" ]

If $a$ is chosen randomly from the set $\{1,2,3,4,5\}$ and $b$ is chosen randomly from the set $\{6,7,8\}$, what is the probability that $a^{b}$ is an even number?

[ "$\\frac{2}{5}$" ]

A bag contains some blue and some green hats. On each turn, Julia removes one hat without looking, with each hat in the bag being equally likely to be chosen. If it is green, she adds a blue hat into the bag from her supply of extra hats, and if it is blue, she adds a green hat to the bag. The bag initially contains 4 blue hats and 2 green hats. What is the probability that the bag again contains 4 blue hats and 2 green hats after two turns?

[ "$\\frac{11}{18}$" ]

Suppose that, for some angles $x$ and $y$, $$ \begin{aligned} & \sin ^{2} x+\cos ^{2} y=\frac{3}{2} a \\ & \cos ^{2} x+\sin ^{2} y=\frac{1}{2} a^{2} \end{aligned} $$ Determine the possible value(s) of $a$.

[ "1" ]

The sequence $2,5,10,50,500, \ldots$ is formed so that each term after the second is the product of the two previous terms. The 15 th term ends with exactly $k$ zeroes. What is the value of $k$ ?

[ "233" ]

If $\log _{2} x-2 \log _{2} y=2$, determine $y$, as a function of $x$

[ "$\\frac{1}{2},\\sqrt{x}$" ]

Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. Determine all real numbers $k$ for which $f(x)$ is constant for all values of $x$.

[ "$-\\frac{3}{2}$" ]

Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. If $k=-0.7$, determine all solutions to the equation $f(x)=0$.

[ "$x=\\frac{1}{6} \\pi+\\pi k, \\frac{1}{3} \\pi+\\pi k, \\frac{2}{3} \\pi+\\pi k, \\frac{5}{6} \\pi+\\pi k$" ]

Define $f(x)=\sin ^{6} x+\cos ^{6} x+k\left(\sin ^{4} x+\cos ^{4} x\right)$ for some real number $k$. Determine all real numbers $k$ for which there exists a real number $c$ such that $f(c)=0$.

[ "$[-1,-\\frac{1}{2}]$" ]

Hexagon $A B C D E F$ has vertices $A(0,0), B(4,0), C(7,2), D(7,5), E(3,5)$, $F(0,3)$. What is the area of hexagon $A B C D E F$ ?

[ "29" ]

A list $a_{1}, a_{2}, a_{3}, a_{4}$ of rational numbers is defined so that if one term is equal to $r$, then the next term is equal to $1+\frac{1}{1+r}$. For example, if $a_{3}=\frac{41}{29}$, then $a_{4}=1+\frac{1}{1+(41 / 29)}=\frac{99}{70}$. If $a_{3}=\frac{41}{29}$, what is the value of $a_{1} ?$

[ "$\\frac{7}{5}$" ]

A hollow cylindrical tube has a radius of $10 \mathrm{~mm}$ and a height of $100 \mathrm{~mm}$. The tube sits flat on one of its circular faces on a horizontal table. The tube is filled with water to a depth of $h \mathrm{~mm}$. A solid cylindrical rod has a radius of $2.5 \mathrm{~mm}$ and a height of $150 \mathrm{~mm}$. The rod is inserted into the tube so that one of its circular faces sits flat on the bottom of the tube. The height of the water in the tube is now $64 \mathrm{~mm}$. Determine the value of $h$.

[ "60" ]

A function $f$ has the property that $f\left(\frac{2 x+1}{x}\right)=x+6$ for all real values of $x \neq 0$. What is the value of $f(4) ?$

[ "$\\frac{13}{2}$" ]

Determine all real numbers $a, b$ and $c$ for which the graph of the function $y=\log _{a}(x+b)+c$ passes through the points $P(3,5), Q(5,4)$ and $R(11,3)$.

[ "$\\frac{1}{3},-2,5$" ]

A computer is programmed to choose an integer between 1 and 99, inclusive, so that the probability that it selects the integer $x$ is equal to $\log _{100}\left(1+\frac{1}{x}\right)$. Suppose that the probability that $81 \leq x \leq 99$ is equal to 2 times the probability that $x=n$ for some integer $n$. What is the value of $n$ ?

[ "9" ]

What is the smallest positive integer $x$ for which $\frac{1}{32}=\frac{x}{10^{y}}$ for some positive integer $y$ ?

[ "3125" ]

Determine all possible values for the area of a right-angled triangle with one side length equal to 60 and with the property that its side lengths form an arithmetic sequence. (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, $3,5,7,9$ are the first four terms of an arithmetic sequence.)

[ "2400, 1350, 864" ]

Amrita and Zhang cross a lake in a straight line with the help of a one-seat kayak. Each can paddle the kayak at $7 \mathrm{~km} / \mathrm{h}$ and swim at $2 \mathrm{~km} / \mathrm{h}$. They start from the same point at the same time with Amrita paddling and Zhang swimming. After a while, Amrita stops the kayak and immediately starts swimming. Upon reaching the kayak (which has not moved since Amrita started swimming), Zhang gets in and immediately starts paddling. They arrive on the far side of the lake at the same time, 90 minutes after they began. Determine the amount of time during these 90 minutes that the kayak was not being paddled.

[ "50" ]

Determine all pairs $(x, y)$ of real numbers that satisfy the system of equations $$ \begin{aligned} x\left(\frac{1}{2}+y-2 x^{2}\right) & =0 \\ y\left(\frac{5}{2}+x-y\right) & =0 \end{aligned} $$

[ "$(0,0),(0, \\frac{5}{2}),(\\frac{1}{2}, 0),(-\\frac{1}{2}, 0),(\\frac{3}{2}, 4),(-1, \\frac{3}{2})$" ]

Determine all real numbers $x>0$ for which $$ \log _{4} x-\log _{x} 16=\frac{7}{6}-\log _{x} 8 $$

[ "$2^{-2 / 3}$, $8$" ]

The string $A A A B B B A A B B$ is a string of ten letters, each of which is $A$ or $B$, that does not include the consecutive letters $A B B A$. The string $A A A B B A A A B B$ is a string of ten letters, each of which is $A$ or $B$, that does include the consecutive letters $A B B A$. Determine, with justification, the total number of strings of ten letters, each of which is $A$ or $B$, that do not include the consecutive letters $A B B A$.

[ "631" ]

Let $k$ be a positive integer with $k \geq 2$. Two bags each contain $k$ balls, labelled with the positive integers from 1 to $k$. André removes one ball from each bag. (In each bag, each ball is equally likely to be chosen.) Define $P(k)$ to be the probability that the product of the numbers on the two balls that he chooses is divisible by $k$. Calculate $P(10)$.

[ "$\\frac{27}{100}$" ]

In an arithmetic sequence, the first term is 1 and the last term is 19 . The sum of all the terms in the sequence is 70 . How many terms does the sequence have? (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, 3, 5, 7, 9 is an arithmetic sequence with four terms.)

[ "7" ]

Suppose that $a(x+b(x+3))=2(x+6)$ for all values of $x$. Determine $a$ and $b$.

[ "-2,-2" ]

An integer $n$, with $100 \leq n \leq 999$, is chosen at random. What is the probability that the sum of the digits of $n$ is 24 ?

[ "$\\frac{1}{90}$" ]

The parabola $y=x^{2}-2 x+4$ is translated $p$ units to the right and $q$ units down. The $x$-intercepts of the resulting parabola are 3 and 5 . What are the values of $p$ and $q$ ?

[ "3,4" ]

If $\log _{2} x,\left(1+\log _{4} x\right)$, and $\log _{8} 4 x$ are consecutive terms of a geometric sequence, determine the possible values of $x$. (A geometric sequence is a sequence in which each term after the first is obtained from the previous term by multiplying it by a constant. For example, $3,6,12$ is a geometric sequence with three terms.)

[ "$64,\\frac{1}{4}$" ]

Determine the two pairs of positive integers $(a, b)$ with $a<b$ that satisfy the equation $\sqrt{a}+\sqrt{b}=\sqrt{50}$.

[ "(2,32), (8,18)" ]

Consider the system of equations: $$ \begin{aligned} c+d & =2000 \\ \frac{c}{d} & =k \end{aligned} $$ Determine the number of integers $k$ with $k \geq 0$ for which there is at least one pair of integers $(c, d)$ that is a solution to the system.

[ "20" ]

Determine all real numbers $x$ for which $2 \log _{2}(x-1)=1-\log _{2}(x+2)$.

[ "$\\sqrt{3}$" ]

Consider the function $f(x)=x^{2}-2 x$. Determine all real numbers $x$ that satisfy the equation $f(f(f(x)))=3$.

[ "$3,1,-1,1+\\sqrt{2}, 1-\\sqrt{2}$" ]

Suppose that $x$ satisfies $0<x<\frac{\pi}{2}$ and $\cos \left(\frac{3}{2} \cos x\right)=\sin \left(\frac{3}{2} \sin x\right)$. Determine all possible values of $\sin 2 x$, expressing your answers in the form $\frac{a \pi^{2}+b \pi+c}{d}$ where $a, b, c, d$ are integers.

[ "$\\frac{\\pi^{2}-9}{9}$" ]

For positive integers $a$ and $b$, define $f(a, b)=\frac{a}{b}+\frac{b}{a}+\frac{1}{a b}$. For example, the value of $f(1,2)$ is 3 . Determine the value of $f(2,5)$.

[ "3" ]

For positive integers $a$ and $b$, define $f(a, b)=\frac{a}{b}+\frac{b}{a}+\frac{1}{a b}$. For example, the value of $f(1,2)$ is 3 . Determine all positive integers $a$ for which $f(a, a)$ is an integer.

[ "1" ]

Amir and Brigitte play a card game. Amir starts with a hand of 6 cards: 2 red, 2 yellow and 2 green. Brigitte starts with a hand of 4 cards: 2 purple and 2 white. Amir plays first. Amir and Brigitte alternate turns. On each turn, the current player chooses one of their own cards at random and places it on the table. The cards remain on the table for the rest of the game. A player wins and the game ends when they have placed two cards of the same colour on the table. Determine the probability that Amir wins the game.

[ "$\\frac{7}{15}$" ]

Consider the sequence $t_{1}=1, t_{2}=-1$ and $t_{n}=\left(\frac{n-3}{n-1}\right) t_{n-2}$ where $n \geq 3$. What is the value of $t_{1998}$ ?

[ "$\\frac{-1}{1997}$" ]

The $n$th term of an arithmetic sequence is given by $t_{n}=555-7 n$. If $S_{n}=t_{1}+t_{2}+\ldots+t_{n}$, determine the smallest value of $n$ for which $S_{n}<0$.

[ "158" ]

If $x$ and $y$ are real numbers, determine all solutions $(x, y)$ of the system of equations $$ \begin{aligned} & x^{2}-x y+8=0 \\ & x^{2}-8 x+y=0 \end{aligned} $$

[ "$(-1,-9),(4+2 \\sqrt{2}, 8),(4-2 \\sqrt{2}, 8)$" ]

The equations $x^{2}+5 x+6=0$ and $x^{2}+5 x-6=0$ each have integer solutions whereas only one of the equations in the pair $x^{2}+4 x+5=0$ and $x^{2}+4 x-5=0$ has integer solutions. Determine $q$ in terms of $a$ and $b$.

[ "$\\frac{a b}{2}$" ]

Determine all values of $k$, with $k \neq 0$, for which the parabola $$ y=k x^{2}+(5 k+3) x+(6 k+5) $$ has its vertex on the $x$-axis.

[ "$-1,-9$" ]

The function $f(x)$ satisfies the equation $f(x)=f(x-1)+f(x+1)$ for all values of $x$. If $f(1)=1$ and $f(2)=3$, what is the value of $f(2008)$ ?

[ "-1" ]

The numbers $a, b, c$, in that order, form a three term arithmetic sequence (see below) and $a+b+c=60$. The numbers $a-2, b, c+3$, in that order, form a three term geometric sequence. Determine all possible values of $a, b$ and $c$. (An arithmetic sequence is a sequence in which each term after the first is obtained from the previous term by adding a constant. For example, $3,5,7$ is an arithmetic sequence with three terms. A geometric sequence is a sequence in which each term after the first is obtained from the previous term by multiplying it by a constant. For example, $3,6,12$ is a geometric sequence with three terms.) Present your answer in the form of coordinates (e.g. (1, 2, 3) for a=1, b=2, c=3).

[ "$(27,20,13), (18,20,22)$" ]

The average of three consecutive multiples of 3 is $a$. The average of four consecutive multiples of 4 is $a+27$. The average of the smallest and largest of these seven integers is 42 . Determine the value of $a$.

[ "27" ]

Billy and Crystal each have a bag of 9 balls. The balls in each bag are numbered from 1 to 9. Billy and Crystal each remove one ball from their own bag. Let $b$ be the sum of the numbers on the balls remaining in Billy's bag. Let $c$ be the sum of the numbers on the balls remaining in Crystal's bag. Determine the probability that $b$ and $c$ differ by a multiple of 4 .

[ "$\\frac{7}{27}$" ]

The equation $2^{x+2} 5^{6-x}=10^{x^{2}}$ has two real solutions. Determine these two solutions.

[ "$2,-\\log _{10} 250$" ]

Determine all real solutions to the system of equations $$ \begin{aligned} & x+\log _{10} x=y-1 \\ & y+\log _{10}(y-1)=z-1 \\ & z+\log _{10}(z-2)=x+2 \end{aligned} $$ and prove that there are no more solutions.

[ "$1,2,3$" ]

The positive integers 34 and 80 have exactly two positive common divisors, namely 1 and 2. How many positive integers $n$ with $1 \leq n \leq 30$ have the property that $n$ and 80 have exactly two positive common divisors?

[ "9" ]

A function $f$ is defined so that - $f(1)=1$, - if $n$ is an even positive integer, then $f(n)=f\left(\frac{1}{2} n\right)$, and - if $n$ is an odd positive integer with $n>1$, then $f(n)=f(n-1)+1$. For example, $f(34)=f(17)$ and $f(17)=f(16)+1$. Determine the value of $f(50)$.

[ "3" ]

The perimeter of equilateral $\triangle P Q R$ is 12. The perimeter of regular hexagon $S T U V W X$ is also 12. What is the ratio of the area of $\triangle P Q R$ to the area of $S T U V W X$ ?

[ "$\\frac{2}{3}$" ]

For how many integers $k$ with $0<k<18$ is $\frac{5 \sin \left(10 k^{\circ}\right)-2}{\sin ^{2}\left(10 k^{\circ}\right)} \geq 2$ ?

[ "13" ]

Eight people, including triplets Barry, Carrie and Mary, are going for a trip in four canoes. Each canoe seats two people. The eight people are to be randomly assigned to the four canoes in pairs. What is the probability that no two of Barry, Carrie and Mary will be in the same canoe?

[ "$\\frac{4}{7}$" ]

Diagonal $W Y$ of square $W X Y Z$ has slope 2. Determine the sum of the slopes of $W X$ and $X Y$.

[ "$-\\frac{8}{3}$" ]

Determine all values of $x$ such that $\log _{2 x}(48 \sqrt[3]{3})=\log _{3 x}(162 \sqrt[3]{2})$.

[ "$\\sqrt{6}$" ]

In an infinite array with two rows, the numbers in the top row are denoted $\ldots, A_{-2}, A_{-1}, A_{0}, A_{1}, A_{2}, \ldots$ and the numbers in the bottom row are denoted $\ldots, B_{-2}, B_{-1}, B_{0}, B_{1}, B_{2}, \ldots$ For each integer $k$, the entry $A_{k}$ is directly above the entry $B_{k}$ in the array, as shown: | $\ldots$ | $A_{-2}$ | $A_{-1}$ | $A_{0}$ | $A_{1}$ | $A_{2}$ | $\ldots$ | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | $\ldots$ | $B_{-2}$ | $B_{-1}$ | $B_{0}$ | $B_{1}$ | $B_{2}$ | $\ldots$ | For each integer $k, A_{k}$ is the average of the entry to its left, the entry to its right, and the entry below it; similarly, each entry $B_{k}$ is the average of the entry to its left, the entry to its right, and the entry above it. In one such array, $A_{0}=A_{1}=A_{2}=0$ and $A_{3}=1$. Determine the value of $A_{4}$.

[ "6" ]

The populations of Alphaville and Betaville were equal at the end of 1995. The population of Alphaville decreased by $2.9 \%$ during 1996, then increased by $8.9 \%$ during 1997 , and then increased by $6.9 \%$ during 1998 . The population of Betaville increased by $r \%$ in each of the three years. If the populations of the towns are equal at the end of 1998, determine the value of $r$ correct to one decimal place.

[ "4.2" ]

Determine the coordinates of the points of intersection of the graphs of $y=\log _{10}(x-2)$ and $y=1-\log _{10}(x+1)$.

[ "$(4, \\log _{10} 2)$" ]

Charlie was born in the twentieth century. On his birthday in the present year (2014), he notices that his current age is twice the number formed by the rightmost two digits of the year in which he was born. Compute the four-digit year in which Charlie was born.

[ "1938" ]

Let $A, B$, and $C$ be randomly chosen (not necessarily distinct) integers between 0 and 4 inclusive. Pat and Chris compute the value of $A+B \cdot C$ by two different methods. Pat follows the proper order of operations, computing $A+(B \cdot C)$. Chris ignores order of operations, choosing instead to compute $(A+B) \cdot C$. Compute the probability that Pat and Chris get the same answer.

[ "$\\frac{9}{25}$" ]

Bobby, Peter, Greg, Cindy, Jan, and Marcia line up for ice cream. In an acceptable lineup, Greg is ahead of Peter, Peter is ahead of Bobby, Marcia is ahead of Jan, and Jan is ahead of Cindy. For example, the lineup with Greg in front, followed by Peter, Marcia, Jan, Cindy, and Bobby, in that order, is an acceptable lineup. Compute the number of acceptable lineups.

[ "20" ]

In triangle $A B C, a=12, b=17$, and $c=13$. Compute $b \cos C-c \cos B$.

[ "10" ]

The sequence of words $\left\{a_{n}\right\}$ is defined as follows: $a_{1}=X, a_{2}=O$, and for $n \geq 3, a_{n}$ is $a_{n-1}$ followed by the reverse of $a_{n-2}$. For example, $a_{3}=O X, a_{4}=O X O, a_{5}=O X O X O$, and $a_{6}=O X O X O O X O$. Compute the number of palindromes in the first 1000 terms of this sequence.

[ "667" ]

Compute the smallest positive integer $n$ such that $214 \cdot n$ and $2014 \cdot n$ have the same number of divisors.

[ "19133" ]

Let $N$ be the least integer greater than 20 that is a palindrome in both base 20 and base 14 . For example, the three-digit base-14 numeral (13)5(13) ${ }_{14}$ (representing $13 \cdot 14^{2}+5 \cdot 14^{1}+13 \cdot 14^{0}$ ) is a palindrome in base 14 , but not in base 20 , and the three-digit base-14 numeral (13)31 14 is not a palindrome in base 14 . Compute the base-10 representation of $N$.

[ "105" ]

$\quad$ Compute the greatest integer $k \leq 1000$ such that $\left(\begin{array}{c}1000 \\ k\end{array}\right)$ is a multiple of 7 .

[ "979" ]

An integer-valued function $f$ is called tenuous if $f(x)+f(y)>x^{2}$ for all positive integers $x$ and $y$. Let $g$ be a tenuous function such that $g(1)+g(2)+\cdots+g(20)$ is as small as possible. Compute the minimum possible value for $g(14)$.

[ "136" ]