Difference between revisions of "2008 AMC 10B Problems"

Latest revision as of 19:20, 31 July 2024

2008 AMC 10B (Answer Key) Printable versions: Wiki • AoPS Resources • PDF
Instructions This is a 25-question, multiple choice test. Each question is followed by answers marked A, B, C, D and E. Only one of these is correct. You will receive 6 points for each correct answer, 2.5 points for each problem left unanswered if the year is before 2006, 1.5 points for each problem left unanswered if the year is after 2006, and 0 points for each incorrect answer. No aids are permitted other than scratch paper, graph paper, ruler, compass, protractor and erasers (and calculators that are accepted for use on the SAT if before 2006. No problems on the test will require the use of a calculator). Figures are not necessarily drawn to scale. You will have 75 minutes working time to complete the test.
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25

Problem 1

A basketball player made $5$ baskets during a game. Each basket was worth either $2$ or $3$ points. How many different numbers could represent the total points scored by the player?

$\mathrm{(A)}\ 2\qquad\mathrm{(B)}\ 3\qquad\mathrm{(C)}\ 4\qquad\mathrm{(D)}\ 5\qquad\mathrm{(E)}\ 6$

Solution

Problem 2

A $4\times 4$ block of calendar dates is shown. The order of the numbers in the second row is to be reversed. Then the order of the numbers in the fourth row is to be reversed. Finally, the numbers on each diagonal are to be added. What will be the positive difference between the two diagonal sums?

$\begin{tabular}[t]{|c|c|c|c|} \multicolumn{4}{c}{}\\\hline 1&2&3&4\\\hline 8&9&10&11\\\hline 15&16&17&18\\\hline 22&23&24&25\\\hline \end{tabular}$

$\textbf{(A)}\ 2 \qquad \textbf{(B)}\ 4 \qquad \textbf{(C)}\ 6 \qquad \textbf{(D)}\ 8 \qquad \textbf{(E)}\ 10$

Solution

Problem 3

Assume that $x$ is a positive real number. Which is equivalent to $\sqrt[3]{x\sqrt{x}}$ ?

$\mathrm{(A)}\ x^{1/6}\qquad\mathrm{(B)}\ x^{1/4}\qquad\mathrm{(C)}\ x^{3/8}\qquad\mathrm{(D)}\ x^{1/2}\qquad\mathrm{(E)}\ x$

Solution

Problem 4

A semipro baseball league has teams with $21$ players each. League rules state that a player must be paid at least $\textdollar 15,000$ and that the total of all players' salaries for each team cannot exceed $\textdollar 700,000.$ What is the maximum possible salary, in dollars, for a single player?

$\mathrm{(A)}\ 270,000\qquad\mathrm{(B)}\ 385,000\qquad\mathrm{(C)}\ 400,000\qquad\mathrm{(D)}\ 430,000\qquad\mathrm{(E)}\ 700,000$

Solution

Problem 5

For real numbers $a$ and $b$ , define $a \textdollar b$ $=(a-b)^2$ . What is $(x-y)^2\textdollar(y-x)^2$ ?

$\mathrm{(A)}\ 0\qquad\mathrm{(B)}\ x^2+y^2\qquad\mathrm{(C)}\ 2x^2\qquad\mathrm{(D)}\ 2y^2\qquad\mathrm{(E)}\ 4xy$

Solution

Problem 6

Points $B$ and $C$ lie on $AD$ . The length of $AB$ is $4$ times the length of $BD$ , and the length of $AC$ is $9$ times the length of $CD$ . The length of $BC$ is what fraction of the length of $AD$ ?

$\mathrm{(A)}\ 1/36\qquad\mathrm{(B)}\ 1/13\qquad\mathrm{(C)}\ 1/10\qquad\mathrm{(D)}\ 5/36\qquad\mathrm{(E)}\ 1/5$

Solution

Problem 7

An equilateral triangle of side length $10$ is completely filled in by non-overlapping equilateral triangles of side length $1$ . How many small triangles are required?

$\mathrm{(A)}\ 10\qquad\mathrm{(B)}\ 25\qquad\mathrm{(C)}\ 100\qquad\mathrm{(D)}\ 250\qquad\mathrm{(E)}\ 1000$

Solution

Problem 8

A class collects $\textdollar50$ to buy flowers for a classmate who is in the hospital. Roses cost $\textdollar3$ each, and carnations cost $\textdollar2$ each. No other flowers are to be used. How many different bouquets could be purchased for exactly $\textdollar50$ ?

$\mathrm{(A)}\ 1 \qquad \mathrm{(B)}\ 7 \qquad \mathrm{(C)}\ 9 \qquad \mathrm{(D)}\ 16 \qquad \mathrm{(E)}\ 17$

Solution

Problem 9

A quadratic equation $ax^2 - 2ax + b = 0$ has two real solutions. What is the average of these two solutions?

$\mathrm{(A)}\ 1\qquad\mathrm{(B)}\ 2\qquad\mathrm{(C)}\ \frac ba\qquad\mathrm{(D)}\ \frac{2b}a\qquad\mathrm{(E)}\ \sqrt{2b-a}$

Solution

Problem 10

Points $A$ and $B$ are on a circle of radius $5$ and $AB=6$ . Point $C$ is the midpoint of the minor arc $AB$ . What is the length of the line segment $AC$ ?

$\mathrm{(A)}\ \sqrt{10}\qquad\mathrm{(B)}\ \frac{7}{2}\qquad\mathrm{(C)}\ \sqrt{14}\qquad\mathrm{(D)}\ \sqrt{15}\qquad\mathrm{(E)}\ 4$

Solution

Problem 11

Suppose that $(u_n)$ is a sequence of real numbers satisfying $u_{n+2}=2u_{n+1}+u_n$ ,

and that $u_3=9$ and $u_6=128$ . What is $u_5$ ?

$\mathrm{(A)}\ 40\qquad\mathrm{(B)}\ 53\qquad\mathrm{(C)}\ 68\qquad\mathrm{(D)}\ 88\qquad\mathrm{(E)}\ 104$

Solution

Problem 12

Postman Pete has a pedometer to count his steps. The pedometer records up to 99999 steps, then flips over to 00000 on the next step. Pete plans to determine his mileage for a year. On January 1 Pete sets the pedometer to 00000. During the year, the pedometer flips from 99999 to 00000 forty-four times. On December 31 the pedometer reads 50000. Pete takes 1800 steps per mile. Which of the following is closest to the number of miles Pete walked during the year?

$\mathrm{(A)}\ 2500\qquad\mathrm{(B)}\ 3000\qquad\mathrm{(C)}\ 3500\qquad\mathrm{(D)}\ 4000\qquad\mathrm{(E)}\ 4500$

Solution

Problem 13

For each positive integer $n$ , the mean of the first $n$ terms of a sequence is $n$ . What is the 2008th term of the sequence?

$\mathrm{(A)}\ {{{2008}}} \qquad \mathrm{(B)}\ {{{4015}}} \qquad \mathrm{(C)}\ {{{4016}}} \qquad \mathrm{(D)}\ {{{4,030,056}}} \qquad \mathrm{(E)}\ {{{4,032,064}}}$

Solution

Problem 14

Triangle $OAB$ has $O=(0,0)$ , $B=(5,0)$ , and $A$ in the first quadrant. In addition, $\angle ABO=90^\circ$ and $\angle AOB=30^\circ$ . Suppose that $OA$ is rotated $90^\circ$ counterclockwise about $O$ . What are the coordinates of the image of $A$ ?

$\mathrm{(A)}\ \left( - \frac {10}{3}\sqrt {3},5\right) \qquad \mathrm{(B)}\ \left( - \frac {5}{3}\sqrt {3},5\right) \qquad \mathrm{(C)}\ \left(\sqrt {3},5\right) \qquad \mathrm{(D)}\ \left(\frac {5}{3}\sqrt {3},5\right) \qquad \mathrm{(E)}\ \left(\frac {10}{3}\sqrt {3},5\right)$

Solution

Problem 15

How many right triangles have integer leg lengths $a$ and $b$ and a hypotenuse of length $b+1$ , where $b<100$ ?

$\mathrm{(A)}\ 6\qquad\mathrm{(B)}\ 7\qquad\mathrm{(C)}\ 8\qquad\mathrm{(D)}\ 9\qquad\mathrm{(E)}\ 10$

Solution

Problem 16

Two fair coins are to be tossed once. For each head that results, one fair die is to be rolled. What is the probability that the sum of the die rolls is odd? (Note that if no die is rolled, the sum is $0$ .)

$\mathrm{(A)}\ {{{\frac{3} {8}}}} \qquad \mathrm{(B)}\ {{{\frac{1} {2}}}} \qquad \mathrm{(C)}\ {{{\frac{43} {72}}}} \qquad \mathrm{(D)}\ {{{\frac{5} {8}}}} \qquad \mathrm{(E)}\ {{{\frac{2} {3}}}}$

Solution

Problem 17

A poll shows that $70\%$ of all voters approve of the mayor's work. On three separate occasions a pollster selects a voter at random. What is the probability that on exactly one of these three occasions the voter approves of the mayor's work?

$\mathrm{(A)}\ {{{0.063}}} \qquad \mathrm{(B)}\ {{{0.189}}} \qquad \mathrm{(C)}\ {{{0.233}}} \qquad \mathrm{(D)}\ {{{0.333}}} \qquad \mathrm{(E)}\ {{{0.441}}}$

Solution

Problem 18

Bricklayer Brenda would take nine hours to build a chimney alone, and Bricklayer Brandon would take $10$ hours to build it alone. When they work together, they talk a lot, and their combined output decreases by $10$ bricks per hour. Working together, they build the chimney in $5$ hours. How many bricks are in the chimney?

$\mathrm{(A)}\ 500\qquad\mathrm{(B)}\ 900\qquad\mathrm{(C)}\ 950\qquad\mathrm{(D)}\ 1000\qquad\mathrm{(E)}\ 1900$

Solution

Problem 19

A cylindrical tank with radius $4$ feet and height $9$ feet is lying on its side. The tank is filled with water to a depth of $2$ feet. What is the volume of water, in cubic feet?

$\mathrm{(A)}\ 24\pi - 36 \sqrt {2} \qquad \mathrm{(B)}\ 24\pi - 24 \sqrt {3} \qquad \mathrm{(C)}\ 36\pi - 36 \sqrt {3} \qquad \mathrm{(D)}\ 36\pi - 24 \sqrt {2} \qquad \mathrm{(E)}\ 48\pi - 36 \sqrt {3}$

Solution

Problem 20

The faces of a cubical die are marked with the numbers $1$ , $2$ , $2$ , $3$ , $3$ , and $4$ . The faces of another die are marked with the numbers $1$ , $3$ , $4$ , $5$ , $6$ , and $8$ . Both dice are thrown. What is the probability that the sum of the top two numbers will be $5$ , $7$ , or $9$ ?

$\mathrm{(A)}\ 5/18\qquad\mathrm{(B)}\ 7/18\qquad\mathrm{(C)}\ 11/18\qquad\mathrm{(D)}\ 3/4\qquad\mathrm{(E)}\ 8/9$

Solution

Problem 21

Ten chairs are evenly spaced around a round table and numbered clockwise from $1$ through $10$ . Five married couples are to sit in the chairs with men and women alternating, and no one is to sit either next to or across from his/her spouse. How many seating arrangements are possible?

$\mathrm{(A)}\ 240\qquad\mathrm{(B)}\ 360\qquad\mathrm{(C)}\ 480\qquad\mathrm{(D)}\ 540\qquad\mathrm{(E)}\ 720$

Solution

Problem 22

Three red beads, two white beads, and one blue bead are placed in line in random order. What is the probability that no two neighboring beads are the same color?

$\mathrm{(A)}\ 1/12\qquad\mathrm{(B)}\ 1/10\qquad\mathrm{(C)}\ 1/6\qquad\mathrm{(D)}\ 1/3\qquad\mathrm{(E)}\ 1/2$

Solution

Problem 23

A rectangular floor measures $a$ by $b$ feet, where $a$ and $b$ are positive integers with $b > a$ . An artist paints a rectangle on the floor with the sides of the rectangle parallel to the sides of the floor. The unpainted part of the floor forms a border of width 1 foot around the painted rectangle and occupies half of the area of the entire floor. How many possibilities are there for the ordered pair $(a, b)$ ?

$\mathrm{(A)}\ 1\qquad\mathrm{(B)}\ 2\qquad\mathrm{(C)}\ 3\qquad\mathrm{(D)}\ 4\qquad\mathrm{(E)}\ 5$

Solution

Problem 24

Quadrilateral $ABCD$ has $AB = BC = CD$ , angle $ABC = 70^\circ$ and angle $BCD = 170^\circ$ . What is the measure of angle $BAD$ ?

$\mathrm{(A)}\ 75\qquad\mathrm{(B)}\ 80\qquad\mathrm{(C)}\ 85\qquad\mathrm{(D)}\ 90\qquad\mathrm{(E)}\ 95$

Solution

Problem 25

Michael walks at the rate of $5$ feet per second on a long straight path. Trash pails are located every $200$ feet along the path. A garbage truck travels at $10$ feet per second in the same direction as Michael and stops for $30$ seconds at each pail. As Michael passes a pail, he notices the truck ahead of him just leaving the next pail. How many times will Michael and the truck meet?

$\mathrm{(A)}\ 4\qquad\mathrm{(B)}\ 5\qquad\mathrm{(C)}\ 6\qquad\mathrm{(D)}\ 7\qquad\mathrm{(E)}\ 8$

Solution

2008 AMC 10B (Problems • Answer Key • Resources)
Preceded by 2008 AMC 10A Problems	Followed by 2009 AMC 10A Problems
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Difference between revisions of "2008 AMC 10B Problems"

Latest revision as of 19:20, 31 July 2024

Contents

Problem 1

Problem 2

Problem 3

Problem 4

Problem 5

Problem 6

Problem 7

Problem 8

Problem 9

Problem 10

Problem 11

Problem 12

Problem 13

Problem 14

Problem 15

Problem 16

Problem 17

Problem 18

Problem 19

Problem 20

Problem 21

Problem 22

Problem 23

Problem 24

Problem 25

See also

@@ Line 1: / Line 1: @@
+{{AMC10 Problems|year=2008|ab=B}}
 ==Problem 1==
-A basketball player made 5 baskets during a game. Each basket was worth either 2 or 3 points. How many different numbers could represent the total points scored by the player?
+A basketball player made <math>5</math> baskets during a game. Each basket was worth either <math>2</math> or <math>3</math> points. How many different numbers could represent the total points scored by the player?
+<math>\mathrm{(A)}\ 2\qquad\mathrm{(B)}\ 3\qquad\mathrm{(C)}\ 4\qquad\mathrm{(D)}\ 5\qquad\mathrm{(E)}\ 6</math>
+[[2008 AMC 10B Problems/Problem 1|Solution]]
-<math>\textbf{(A)} 2 \qquad \textbf{(B)} 3 \qquad \textbf{(C)} 4 \qquad \textbf{(D)} 5 \qquad \textbf{(E)} 6</math>
-([[2008 AMC 10B Problems/Problem 1|Solution]])
 ==Problem 2==
-A <math>4\times 4</math> block of calendar dates has the numbers <math>1</math> through <math>4</math> in the first row, <math>8</math> though <math>11</math> in the second, <math>15</math> though <math>18</math> in the third, and <math>22</math> through <math>25</math> in the fourth. The order of the numbers in the second and the fourth rows are reversed. The numbers on each diagonal are added. What will be the positive difference between the diagonal sums?
+A <math>4\times 4</math> block of calendar dates is shown. The order of the numbers in the second row is to be reversed. Then the order of the numbers in the fourth row is to be reversed. Finally, the numbers on each diagonal are to be added. What will be the positive difference between the two diagonal sums?
+<math>\begin{tabular}[t]{|c|c|c|c|}
+\multicolumn{4}{c}{}\\\hline
+&2&3&4\\\hline
+&9&10&11\\\hline
+&16&17&18\\\hline
+&23&24&25\\\hline
+\end{tabular}</math>
+<math>\textbf{(A)}\ 2 \qquad \textbf{(B)}\ 4 \qquad \textbf{(C)}\ 6 \qquad \textbf{(D)}\ 8 \qquad \textbf{(E)}\ 10</math>
+[[2008 AMC 10B Problems/Problem 2|Solution]]
-<math>\textbf{(A)} 2 \qquad \textbf{(B)} 4 \qquad \textbf{(C)} 6 \qquad \textbf{(D)} 8 \qquad \textbf{(E)} 10</math>
-([[2008 AMC 10B Problems/Problem 2|Solution]])
 ==Problem 3==
 Assume that <math>x</math> is a [[positive]] [[real number]]. Which is equivalent to <math>\sqrt[3]{x\sqrt{x}}</math>?
-<math>\textbf{(A)} x^{1/6} \qquad \textbf{(B)} x^{1/4} \qquad \textbf{(C)} </math>x^{3/8} \qquad \textbf{(D)} x^{1/2} \qquad \textbf{(E)} x$
+<math>\mathrm{(A)}\ x^{1/6}\qquad\mathrm{(B)}\ x^{1/4}\qquad\mathrm{(C)}\ x^{3/8}\qquad\mathrm{(D)}\ x^{1/2}\qquad\mathrm{(E)}\ x</math>
-([[2008 AMC 10B Problems/Problem 3|Solution]])
+[[2008 AMC 10B Problems/Problem 3|Solution]]
 ==Problem 4==
-A semipro baseball league has teams with 21 players each. League rules state that a player must be paid at least <dollar/>15,000 and that the total of all players' salaries for each team cannot exceed <dollar/>700,000. What is the maximum possible salary, in dollars, for a single player?
+A semipro baseball league has teams with <math>21</math> players each. League rules state that a player must be paid at least <math>\textdollar 15,000</math> and that the total of all players' salaries for each team cannot exceed <math>\textdollar 700,000.</math> What is the maximum possible salary, in dollars, for a single player?
+<math>\mathrm{(A)}\ 270,000\qquad\mathrm{(B)}\ 385,000\qquad\mathrm{(C)}\ 400,000\qquad\mathrm{(D)}\ 430,000\qquad\mathrm{(E)}\ 700,000</math>
+[[2008 AMC 10B Problems/Problem 4|Solution]]
-<math>\textbf{(A)} 270,000 \qquad \textbf{(B)} 385,000 \qquad \textbf{(C)} 400,000 \qquad \textbf{(D)} 430,000 \qquad \textbf{(E)} 700,000</math>
-([[2008 AMC 10B Problems/Problem 4|Solution]])
 ==Problem 5==
-For [[real number]]s <math>a</math> and <math>b</math>, define <math>a\</math> b=(a-b)^2<math>. What is </math>(x-y)^2\<math> (y-x)^2</math>?
+For [[real number]]s <math>a</math> and <math>b</math>, define <math>a \textdollar b</math> <math>=(a-b)^2</math>. What is <math>(x-y)^2\textdollar(y-x)^2</math>?
+<math>\mathrm{(A)}\ 0\qquad\mathrm{(B)}\ x^2+y^2\qquad\mathrm{(C)}\ 2x^2\qquad\mathrm{(D)}\ 2y^2\qquad\mathrm{(E)}\ 4xy</math>
+[[2008 AMC 10B Problems/Problem 5|Solution]]
-<math>\textbf{(A)} 0 \qquad \textbf{(B)} x^2+y^2 \qquad \textbf{(C)} 2x^2 \qquad \textbf{(D)} 2y^2 \qquad \textbf{(E)} 4xy</math>
-([[2008 AMC 10B Problems/Problem 5|Solution]])
 ==Problem 6==
+Points <math>B</math> and <math>C</math> lie on <math>AD</math>. The length of <math>AB</math> is <math>4</math> times the length of <math>BD</math>, and the length of <math>AC</math> is <math>9</math> times the length of <math>CD</math>. The length of <math>BC</math> is what fraction of the length of <math>AD</math>?
+<math>\mathrm{(A)}\ 1/36\qquad\mathrm{(B)}\ 1/13\qquad\mathrm{(C)}\ 1/10\qquad\mathrm{(D)}\ 5/36\qquad\mathrm{(E)}\ 1/5</math>
+[[2008 AMC 10B Problems/Problem 6|Solution]]
-([[2008 AMC 10B Problems/Problem 6|Solution]])
 ==Problem 7==
+An equilateral triangle of side length <math>10</math> is completely filled in by non-overlapping equilateral triangles of side length <math>1</math>. How many small triangles are required?
+<math>\mathrm{(A)}\ 10\qquad\mathrm{(B)}\ 25\qquad\mathrm{(C)}\ 100\qquad\mathrm{(D)}\ 250\qquad\mathrm{(E)}\ 1000</math>
+[[2008 AMC 10B Problems/Problem 7|Solution]]
-([[2008 AMC 10B Problems/Problem 7|Solution]])
 ==Problem 8==
+A class collects <math>\textdollar50</math> to buy flowers for a classmate who is in the hospital. Roses cost <math>\textdollar3</math> each, and carnations cost <math>\textdollar2</math> each. No other flowers are to be used. How many different bouquets could be purchased for exactly <math>\textdollar50</math>?
+<math>
+\mathrm{(A)}\ 1
+\qquad
+\mathrm{(B)}\ 7
+\qquad
+\mathrm{(C)}\ 9
+\qquad
+\mathrm{(D)}\ 16
+\qquad
+\mathrm{(E)}\ 17
+</math>
+[[2008 AMC 10B Problems/Problem 8|Solution]]
-([[2008 AMC 10B Problems/Problem 8|Solution]])
 ==Problem 9==
+A quadratic equation <math>ax^2 - 2ax + b = 0</math> has two real solutions. What is the average of these two solutions?
+<math>\mathrm{(A)}\ 1\qquad\mathrm{(B)}\ 2\qquad\mathrm{(C)}\ \frac ba\qquad\mathrm{(D)}\ \frac{2b}a\qquad\mathrm{(E)}\ \sqrt{2b-a}</math>
+[[2008 AMC 10B Problems/Problem 9|Solution]]
-([[2008 AMC 10B Problems/Problem 9|Solution]])
 ==Problem 10==
+Points <math>A</math> and <math>B</math> are on a circle of radius <math>5</math> and <math>AB=6</math>. Point <math>C</math> is the [[midpoint]] of the minor arc <math>AB</math>. What is the length of the line segment <math>AC</math>?
+<math>\mathrm{(A)}\ \sqrt{10}\qquad\mathrm{(B)}\ \frac{7}{2}\qquad\mathrm{(C)}\ \sqrt{14}\qquad\mathrm{(D)}\ \sqrt{15}\qquad\mathrm{(E)}\ 4</math>
+[[2008 AMC 10B Problems/Problem 10|Solution]]
-([[2008 AMC 10B Problems/Problem 10|Solution]])
 ==Problem 11==
+Suppose that <math>(u_n)</math> is a [[sequence]] of real numbers satisfying <math>u_{n+2}=2u_{n+1}+u_n</math>,
+and that <math>u_3=9</math> and <math>u_6=128</math>. What is <math>u_5</math>?
+<math>\mathrm{(A)}\ 40\qquad\mathrm{(B)}\ 53\qquad\mathrm{(C)}\ 68\qquad\mathrm{(D)}\ 88\qquad\mathrm{(E)}\ 104</math>
+[[2008 AMC 10B Problems/Problem 11|Solution]]
-([[2008 AMC 10B Problems/Problem 11|Solution]])
 ==Problem 12==
+Postman Pete has a pedometer to count his steps. The pedometer records up to 99999 steps, then flips over to 00000 on the next step. Pete plans to determine his mileage for a year. On January 1 Pete sets the pedometer to 00000. During the year, the pedometer flips from 99999 to 00000 forty-four
+times. On December 31 the pedometer reads 50000. Pete takes 1800 steps per mile. Which of the following is closest to the number of miles Pete walked during the year?
+<math>\mathrm{(A)}\ 2500\qquad\mathrm{(B)}\ 3000\qquad\mathrm{(C)}\ 3500\qquad\mathrm{(D)}\ 4000\qquad\mathrm{(E)}\ 4500</math>
+[[2008 AMC 10B Problems/Problem 12|Solution]]
-([[2008 AMC 10B Problems/Problem 12|Solution]])
 ==Problem 13==
+For each positive integer <math>n</math>, the mean of the first <math>n</math> terms of a sequence is <math>n</math>. What is the 2008th term of the sequence?
+<math>\mathrm{(A)}\ {{{2008}}} \qquad \mathrm{(B)}\ {{{4015}}} \qquad \mathrm{(C)}\ {{{4016}}} \qquad \mathrm{(D)}\ {{{4,030,056}}} \qquad \mathrm{(E)}\ {{{4,032,064}}}</math>
+[[2008 AMC 10B Problems/Problem 13|Solution]]
-([[2008 AMC 10B Problems/Problem 13|Solution]])
 ==Problem 14==
+Triangle <math>OAB</math> has <math>O=(0,0)</math>, <math>B=(5,0)</math>, and <math>A</math> in the first quadrant. In addition, <math>\angle ABO=90^\circ</math> and <math>\angle AOB=30^\circ</math>. Suppose that <math>OA</math> is rotated <math>90^\circ</math> counterclockwise about <math>O</math>. What are the coordinates of the image of <math>A</math>?
+<math>
+\mathrm{(A)}\ \left( - \frac {10}{3}\sqrt {3},5\right)
+\qquad
+\mathrm{(B)}\ \left( - \frac {5}{3}\sqrt {3},5\right)
+\qquad
+\mathrm{(C)}\ \left(\sqrt {3},5\right)
+\qquad
+\mathrm{(D)}\ \left(\frac {5}{3}\sqrt {3},5\right)
+\qquad
+\mathrm{(E)}\ \left(\frac {10}{3}\sqrt {3},5\right)
+</math>
+[[2008 AMC 10B Problems/Problem 14|Solution]]
-([[2008 AMC 10B Problems/Problem 14|Solution]])
 ==Problem 15==
+How many right triangles have integer leg lengths <math>a</math> and <math>b</math> and a hypotenuse of length <math>b+1</math>, where <math>b<100</math>?
+<math>\mathrm{(A)}\ 6\qquad\mathrm{(B)}\ 7\qquad\mathrm{(C)}\ 8\qquad\mathrm{(D)}\ 9\qquad\mathrm{(E)}\ 10</math>
+[[2008 AMC 10B Problems/Problem 15|Solution]]
-([[2008 AMC 10B Problems/Problem 15|Solution]])
 ==Problem 16==
+Two fair coins are to be tossed once. For each head that results, one fair die is to be rolled. What is the probability that the sum of the die rolls is odd? (Note that if no die is rolled, the sum is <math>0</math>.)
+<math>\mathrm{(A)}\ {{{\frac{3} {8}}}} \qquad \mathrm{(B)}\ {{{\frac{1} {2}}}} \qquad \mathrm{(C)}\ {{{\frac{43} {72}}}} \qquad \mathrm{(D)}\ {{{\frac{5} {8}}}} \qquad \mathrm{(E)}\ {{{\frac{2} {3}}}}</math>
+[[2008 AMC 10B Problems/Problem 16|Solution]]
-([[2008 AMC 10B Problems/Problem 16|Solution]])
 ==Problem 17==
+A poll shows that <math>70\%</math> of all voters approve of the mayor's work. On three separate occasions a pollster selects a voter at random. What is the probability that on exactly one of these three occasions the voter approves of the mayor's work?
+<math>\mathrm{(A)}\ {{{0.063}}} \qquad \mathrm{(B)}\ {{{0.189}}} \qquad \mathrm{(C)}\ {{{0.233}}} \qquad \mathrm{(D)}\ {{{0.333}}} \qquad \mathrm{(E)}\ {{{0.441}}}</math>
+[[2008 AMC 10B Problems/Problem 17|Solution]]
-([[2008 AMC 10B Problems/Problem 17|Solution]])
 ==Problem 18==
+Bricklayer Brenda would take nine hours to build a chimney alone, and Bricklayer Brandon would take <math>10</math> hours to build it alone. When they work together, they talk a lot, and their combined output decreases by <math>10</math> bricks per hour. Working together, they build the chimney in <math>5</math> hours. How many bricks are in the chimney?
+<math>\mathrm{(A)}\ 500\qquad\mathrm{(B)}\ 900\qquad\mathrm{(C)}\ 950\qquad\mathrm{(D)}\ 1000\qquad\mathrm{(E)}\ 1900</math>
+[[2008 AMC 10B Problems/Problem 18|Solution]]
-([[2008 AMC 10B Problems/Problem 18|Solution]])
 ==Problem 19==
+A cylindrical tank with radius <math>4</math> feet and height <math>9</math> feet is lying on its side. The tank is filled with water to a depth of <math>2</math> feet. What is the volume of water, in cubic feet?
+<math>
+\mathrm{(A)}\ 24\pi - 36 \sqrt {2}
+\qquad
+\mathrm{(B)}\ 24\pi - 24 \sqrt {3}
+\qquad
+\mathrm{(C)}\ 36\pi - 36 \sqrt {3}
+\qquad
+\mathrm{(D)}\ 36\pi - 24 \sqrt {2}
+\qquad
+\mathrm{(E)}\ 48\pi - 36 \sqrt {3}
+</math>
+[[2008 AMC 10B Problems/Problem 19|Solution]]
-([[2008 AMC 10B Problems/Problem 19|Solution]])
 ==Problem 20==
+The faces of a cubical die are marked with the numbers <math>1</math>, <math>2</math>, <math>2</math>, <math>3</math>, <math>3</math>, and <math>4</math>. The faces of another die are marked with the numbers <math>1</math>, <math>3</math>, <math>4</math>, <math>5</math>, <math>6</math>, and <math>8</math>. Both dice are thrown. What is the probability that the sum of the top two numbers will be <math>5</math>, <math>7</math>, or <math>9</math>?
+<math>\mathrm{(A)}\ 5/18\qquad\mathrm{(B)}\ 7/18\qquad\mathrm{(C)}\ 11/18\qquad\mathrm{(D)}\ 3/4\qquad\mathrm{(E)}\ 8/9</math>
+[[2008 AMC 10B Problems/Problem 20|Solution]]
-([[2008 AMC 10B Problems/Problem 20|Solution]])
 ==Problem 21==
-([[2008 AMC 10B Problems/Problem 21|Solution]])
+Ten chairs are evenly spaced around a round table  and numbered clockwise from <math>1</math> through <math>10</math>. Five married couples are to sit in the chairs with men and women alternating, and no one is to sit either next to or across from his/her spouse. How many seating arrangements are possible?
+<math>\mathrm{(A)}\ 240\qquad\mathrm{(B)}\ 360\qquad\mathrm{(C)}\ 480\qquad\mathrm{(D)}\ 540\qquad\mathrm{(E)}\ 720</math>
+[[2008 AMC 10B Problems/Problem 21|Solution]]
 ==Problem 22==
+Three red beads, two white beads, and one blue bead are placed in line in random order. What is the probability that no two neighboring beads are the same color?
+<math>\mathrm{(A)}\ 1/12\qquad\mathrm{(B)}\ 1/10\qquad\mathrm{(C)}\ 1/6\qquad\mathrm{(D)}\ 1/3\qquad\mathrm{(E)}\ 1/2</math>
+[[2008 AMC 10B Problems/Problem 22|Solution]]
-([[2008 AMC 10B Problems/Problem 22|Solution]])
 ==Problem 23==
+A rectangular floor measures <math>a</math> by <math>b</math> feet, where <math>a</math> and <math>b</math> are positive integers with <math>b > a</math>. An artist paints a rectangle on the floor with the sides of the rectangle parallel to the sides of the floor. The unpainted part of the floor forms a border of width 1 foot around the painted
+rectangle and occupies half of the area of the entire floor. How many possibilities are there for the ordered pair <math>(a, b)</math>?
+<math>\mathrm{(A)}\ 1\qquad\mathrm{(B)}\ 2\qquad\mathrm{(C)}\ 3\qquad\mathrm{(D)}\ 4\qquad\mathrm{(E)}\ 5</math>
+[[2008 AMC 10B Problems/Problem 23|Solution]]
-([[2008 AMC 10B Problems/Problem 23|Solution]])
 ==Problem 24==
+Quadrilateral <math>ABCD</math> has <math>AB = BC = CD</math>, angle <math>ABC = 70^\circ</math> and angle <math>BCD = 170^\circ </math>. What is the measure of angle <math>BAD</math>?
+<math>\mathrm{(A)}\ 75\qquad\mathrm{(B)}\ 80\qquad\mathrm{(C)}\ 85\qquad\mathrm{(D)}\ 90\qquad\mathrm{(E)}\ 95</math>
+[[2008 AMC 10B Problems/Problem 24|Solution]]
-([[2008 AMC 10B Problems/Problem 24|Solution]])
 ==Problem 25==
+Michael walks at the rate of <math>5</math> feet per second on a long straight path. Trash pails are located every <math>200</math> feet along the path. A garbage truck travels at <math>10</math> feet per second in the same direction as Michael and stops for <math>30</math> seconds at each pail. As Michael passes a pail, he notices the truck ahead of him just leaving the next pail. How many times will Michael and the truck meet?
+<math>\mathrm{(A)}\ 4\qquad\mathrm{(B)}\ 5\qquad\mathrm{(C)}\ 6\qquad\mathrm{(D)}\ 7\qquad\mathrm{(E)}\ 8</math>
-([[2008 AMC 10B Problems/Problem 25|Solution]])
+[[2008 AMC 10B Problems/Problem 25|Solution]]
-{{empty}}
+==See also==
+{{AMC10 box|year=2008|ab=B|before=[[2008 AMC 10A Problems]]|after=[[2009 AMC 10A Problems]]}}
+* [[AMC 10]]
+* [[AMC 10 Problems and Solutions]]
+* [[2008 AMC 10B]]
+* [http://www.artofproblemsolving.com/Community/AoPS_Y_MJ_Transcripts.php?mj_id=219 2008 AMC B Math Jam Transcript]
+* [[Mathematics competition resources]]
+{{MAA Notice}}