Difference between revisions of "2002 AMC 12P Problems"

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{{AMC12 Problems|year=2001|ab=}}
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{{AMC12 Problems|year=2002|ab=P}}
 
== Problem 1 ==
 
== Problem 1 ==
The sum of two numbers is <math>S</math>. Suppose <math>3</math> is added to each number and then
+
Which of the following numbers is a perfect square?
each of the resulting numbers is doubled. What is the sum of the final two
 
numbers?
 
  
<math>\text{(A)}\ 2S + 3\qquad \text{(B)}\ 3S + 2\qquad \text{(C)}\ 3S + 6 \qquad\text{(D)} 2S + 6 \qquad \text{(E)}\ 2S + 12</math>
+
<math>\text{(A)}\ 4^5 5^5 6^6 \qquad \text{(B)}\ 4^4 5^6 6^5 \qquad \text{(C)}\ 4^5 5^4 6^6 \qquad\text{(D)} 4^6 5^4 6^5 \qquad \text{(E)}\ 4^6 5^5 6^4</math>
  
[[2001 AMC 12 Problems/Problem 1|Solution]]
+
[[2002 AMC 12P Problems/Problem 2|Solution]]
  
 
== Problem 2 ==
 
== Problem 2 ==
Let <math>P(n)</math> and <math>S(n)</math> denote the product and the sum, respectively, of the digits
+
The function <math>f</math> is given by the table
of the integer <math>n</math>. For example, <math>P(23) = 6</math> and <math>S(23) = 5</math>. Suppose <math>N</math> is a
 
two-digit number such that <math>N = P(N)+S(N)</math>. What is the units digit of <math>N</math>?
 
  
<math>\text{(A)}\ 2\qquad \text{(B)}\ 3\qquad \text{(C)}\ 6\qquad \text{(D)}\ 8\qquad \text{(E)}\ 9</math>
+
If <math>u_0=4</math> and <math>u_{n+1} = f(u_n)</math> for <math>n>=0</math>, find <math>u_2002</math>
  
[[2001 AMC 12 Problems/Problem 2|Solution]]
+
<math>\text{(A)}\ 1\qquad \text{(B)}\ 2\qquad \text{(C)}\ 3\qquad \text{(D)}\ 4\qquad \text{(E)}\ 5</math>
 +
 
 +
[[2002 AMC 12P Problems/Problem 2|Solution]]
  
 
== Problem 3 ==
 
== Problem 3 ==
The state income tax where Kristin lives is levied at the rate of <math>p\%</math> of the first
+
The dimensions of a rectangular box in inches are all positive integers and the volume of the box is <math>2002</math> in^3. Find the minimum possible sum of the three dimensions.
<math>\textdollar 28000</math> of annual income plus <math>(p + 2)\%</math> of any amount above <math>\textdollar 28000</math>. Kristin
 
noticed that the state income tax she paid amounted to <math>(p + 0.25)\%</math> of her
 
annual income. What was her annual income?
 
  
<math>\text{(A)}\ \$28000\qquad \text{(B)}\ \$32000\qquad \text{(C)}\ \$35000\qquad \text{(D)}\ \$42000\qquad \text{(E)}\ \$56000</math>
+
<math>\text{(A)}\ \36\qquad \text{(B)}\ \38\qquad \text{(C)}\ \42\qquad \text{(D)}\ \44\qquad \text{(E)}\ \92</math>
  
[[2001 AMC 12 Problems/Problem 3|Solution]]
+
[[2002 AMC 12P Problems/Problem 3|Solution]]
  
 
== Problem 4 ==
 
== Problem 4 ==
The mean of three numbers is <math>10</math> more than the least of the numbers and <math>15</math>
+
Let <math>a</math> and <math>b</math> be distinct real numbers for which
less than the greatest. The median of the three numbers is <math>5</math>. What is their
+
<cmath>\frac{a}{b} + \frac{a+10b}{b+10a} = 2.</cmath>
sum?
+
Find <math>\frac{a}{b}</math>
  
<math>\text{(A)}\ 5\qquad \text{(B)}\ 20\qquad \text{(C)}\ 25\qquad \text{(D)}\ 30\qquad \text{(E)}\ 36</math>
+
<math>\text{(A)}\ 0.4\qquad \text{(B)}\ 0.5\qquad \text{(C)}\ 0.6\qquad \text{(D)}\ 0.7\qquad \text{(E)}\ 0.8</math>
  
[[2001 AMC 12 Problems/Problem 4|Solution]]
+
[[2002 AMC 12P Problems/Problem 4|Solution]]
  
 
== Problem 5 ==
 
== Problem 5 ==
What is the product of all positive odd integers less than 10000?
+
For how many positive integers <math>m</math> is
 +
<cmath>\frac{2002}{m^2 -2}</cmath>
  
<math>\text{(A)}\ \dfrac{10000!}{(5000!)^2}\qquad \text{(B)}\ \dfrac{10000!}{2^{5000}}\qquad
+
<math>\text{(A)}\ one\qquad \text{(B)}\ two\qquad
\text{(C)}\ \dfrac{9999!}{2^{5000}}\qquad \text{(D)}\ \dfrac{10000!}{2^{5000} \cdot 5000!}\qquad
+
\text{(C)}\ three\qquad \text{(D)}\ four\qquad
\text{(E)}\ \dfrac{5000!}{2^{5000}}</math>
+
\text{(E)}\ five</math>
  
[[2001 AMC 12 Problems/Problem 5|Solution]]
+
[[2002 AMC 12P Problems/Problem 5|Solution]]
  
 
== Problem 6 ==
 
== Problem 6 ==
A telephone number has the form <math>\text{ABC-DEF-GHIJ}</math>, where each letter represents
+
Participation in the local soccer league this year is <math>10%</math> higher than last year. The number of males increased by <math>5%</math> and the number of females increased by <math>20%</math>. What fraction of the soccer league is now female?
a different digit. The digits in each part of the number are in decreasing
 
order; that is, <math>A > B > C</math>, <math>D > E > F</math>, and <math>G > H > I > J</math>. Furthermore,
 
<math>D</math>, <math>E</math>, and <math>F</math> are consecutive even digits; <math>G</math>, <math>H</math>, <math>I</math>, and <math>J</math> are consecutive odd
 
digits; and <math>A + B + C = 9</math>. Find <math>A</math>.
 
  
<math>\text{(A)}\ 4\qquad \text{(B)}\ 5\qquad \text{(C)}\ 6\qquad \text{(D)}\ 7\qquad \text{(E)}\ 8</math>
+
<math>\text{(A)}\ \frac{1}{3}\qquad \text{(B)}\ \frac{4}{11}\qquad \text{(C)}\ \frac{2}{5}\qquad \text{(D)}\ \frac{4}{9}\qquad \text{(E)}\ \frac{1}{2}</math>
  
[[2001 AMC 12 Problems/Problem 6|Solution]]
+
[[2002 AMC 12P Problems/Problem 6|Solution]]
  
 
== Problem 7 ==
 
== Problem 7 ==
  
A charity sells <math>140</math> benefit tickets for a total of <math>\textdollar 2001</math>. Some tickets sell for full price (a whole dollar amount), and the rest sells for half price. How much money is raised by the full-price tickets?
+
How many three-digit numbers have at least one 2 and at least one 3?
  
<math>\text{(A) }\$782\qquad \text{(B) }\$986\qquad \text{(C) }\$1158\qquad \text{(D) }\$1219\qquad \text{(E) }\$1449</math>
+
<math>\text{(A) }\52\qquad \text{(B) }\54\qquad \text{(C) }\56\qquad \text{(D) }\58\qquad \text{(E) }\60</math>
  
[[2001 AMC 12 Problems/Problem 7|Solution]]
+
[[2002 AMC 12P Problems/Problem 7|Solution]]
  
 
== Problem 8 ==
 
== Problem 8 ==
  
Which of the cones listed below can be formed from a <math>252^\circ</math> sector of a circle of radius <math>10</math> by aligning the two straight sides?
+
Let <math>AB</math> be a segment of length <math>26</math>, and let points <math>C</math> and <math>D</math> be located on <math>AB</math> such that <math>AC=1</math> and <math>AD=8</math>. Let <math>E</math> and <math>F</math> be points on one of the semicircles with diameter <math>AB</math> for which <math>EC</math> and <math>FD</math> are perpendicular to <math>AB</math>. Find <math>EF.</math>
 
 
<asy>
 
import graph;
 
unitsize(1.5cm);
 
defaultpen(fontsize(8pt));
 
 
 
draw(Arc((0,0),1,-72,180),linewidth(.8pt));
 
draw(dir(288)--(0,0)--(-1,0),linewidth(.8pt));
 
label("$10$",(-0.5,0),S);
 
draw(Arc((0,0),0.1,-72,180));
 
label("$252^{\circ}$",(0.05,0.05),NE);
 
</asy>
 
 
 
<math>\text{(A) A cone with slant height of } 10 \text{ and radius } 6</math>
 
 
 
<math>\text{(B) A cone with height of } 10 \text{ and radius } 6</math>
 
 
 
<math>\text{(C) A cone with slant height of } 10 \text{ and radius } 7</math>
 
 
 
<math>\text{(D) A cone with height of } 10 \text{ and radius } 7</math>
 
  
<math>\text{(E) A cone with slant height of } 10 \text{ and radius } 8</math>
+
<math>\text{(A) }\5\qquad \text{(B) }\5\sqrt{2}\qquad \text{(C) }\7\qquad \text{(D) }\7\sqrt{2}\qquad \text{(E) }\12</math>
  
[[2001 AMC 12 Problems/Problem 8|Solution]]
+
[[2002 AMC 12P Problems/Problem 8|Solution]]
  
 
== Problem 9 ==
 
== Problem 9 ==
  
Let <math>f</math> be a function satisfying <math>f(xy) = \frac{f(x)}y</math> for all positive real numbers <math>x</math> and <math>y</math>. If <math>f(500) =3</math>, what is the value of <math>f(600)</math>?
+
Two walls and the ceiling of a room meet at right angles at point <math>P.</math> A fly is in the air one meter from one wall, eight meters from the other wall, and nine meters from point <math>P</math>. How many meters is the fly from the ceiling?
  
<math>\text{(A)}\ 1 \qquad \text{(B)}\ 2 \qquad \text{(C)}\ \frac52 \qquad \text{(D)}\ 3 \qquad \text{(E)}\ \frac{18}5</math>
+
<math>\text{(A)}\ \sqrt{13} \qquad \text{(B)}\ 2 \qquad \text{(C)}\ \frac52 \qquad \text{(D)}\ 3 \qquad \text{(E)}\ \frac{18}5</math>
  
[[2001 AMC 12 Problems/Problem 9|Solution]]
+
[[2002 AMC 12P Problems/Problem 9|Solution]]
  
 
== Problem 10 ==
 
== Problem 10 ==
  
The plane is tiled by congruent squares and congruent pentagons as indicated. The percent of the plane that is enclosed by the pentagons is closest to
+
Let <math>f_n (x) = sin^n x + cos^n x.</math> For how many <math>x</math> in <math>[0,π]</math> is it true that
  
 
<math>
 
<math>
\text{(A) }50
+
\text{(A) }2
 
\qquad
 
\qquad
\text{(B) }52
+
\text{(B) }4
 
\qquad
 
\qquad
\text{(C) }54
+
\text{(C) }6
 
\qquad
 
\qquad
\text{(D) }56
+
\text{(D) }8
 
\qquad
 
\qquad
\text{(E) }58
+
\text{(E) }more than 8
 
</math>
 
</math>
  
<asy>
+
[[2002 AMC 12P Problems/Problem 10|Solution]]
unitsize(3mm);
 
defaultpen(linewidth(0.8pt));
 
  
path p1=(0,0)--(3,0)--(3,3)--(0,3)--(0,0);
+
== Problem 11 ==
path p2=(0,1)--(1,1)--(1,0);
 
path p3=(2,0)--(2,1)--(3,1);
 
path p4=(3,2)--(2,2)--(2,3);
 
path p5=(1,3)--(1,2)--(0,2);
 
path p6=(1,1)--(2,2);
 
path p7=(2,1)--(1,2);
 
path[] p=p1^^p2^^p3^^p4^^p5^^p6^^p7;
 
for(int i=0; i<3; ++i)
 
{
 
for(int j=0; j<3; ++j)
 
{
 
draw(shift(3*i,3*j)*p);
 
}
 
}
 
</asy>
 
 
 
[[2001 AMC 12 Problems/Problem 10|Solution]]
 
  
== Problem 11 ==
+
Let <math>t_n = \frac{n(n+1)}{2}</math> be the <math>n</math>th triangular number. Find
  
A box contains exactly five chips, three red and two white. Chips are randomly removed one at a time without replacement until all the red chips are drawn or all the white chips are drawn. What is the probability that the last chip drawn is white?
+
<cmath>\frac{1}{t_1} + \frac{1}{t_2} + \frac{1}{t_3} + ... + \frac{1}{t_2002}</cmath>
  
 
<math>
 
<math>
\text{(A) }\frac {3}{10}
+
\text{(A) }\frac {4003}{2003}
 
\qquad
 
\qquad
\text{(B) }\frac {2}{5}
+
\text{(B) }\frac {2001}{1001}
 
\qquad
 
\qquad
\text{(C) }\frac {1}{2}
+
\text{(C) }\frac {4004}{2003}
 
\qquad
 
\qquad
\text{(D) }\frac {3}{5}
+
\text{(D) }\frac {4001}{2001}
 
\qquad
 
\qquad
\text{(E) }\frac {7}{10}
+
\text{(E) }2
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 11|Solution]]
+
[[2002 AMC 12P Problems/Problem 11|Solution]]
  
 
== Problem 12 ==
 
== Problem 12 ==
  
How many positive integers not exceeding <math>2001</math> are multiples of <math>3</math> or <math>4</math> but not <math>5</math>?
+
What is the maximum value of <math>n</math> for which there is a set of distinct positive integers <math>k_1, k_2, ... k_n</math> for which
  
 +
<math></math>k^2_1
 
<math>
 
<math>
 
\text{(A) }768
 
\text{(A) }768
Line 174: Line 128:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 12|Solution]]
+
[[2002 AMC 12P Problems/Problem 12|Solution]]
  
 
== Problem 13 ==
 
== Problem 13 ==
Line 192: Line 146:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 13|Solution]]
+
[[2002 AMC 12P Problems/Problem 13|Solution]]
  
 
== Problem 14 ==
 
== Problem 14 ==
Line 210: Line 164:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 14|Solution]]
+
[[2002 AMC 12P Problems/Problem 14|Solution]]
  
 
== Problem 15 ==
 
== Problem 15 ==
Line 227: Line 181:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 15|Solution]]
+
[[2002 AMC 12P Problems/Problem 15|Solution]]
  
 
== Problem 16 ==
 
== Problem 16 ==
Line 245: Line 199:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 16|Solution]]
+
[[2002 AMC 12P Problems/Problem 16|Solution]]
  
 
== Problem 17 ==
 
== Problem 17 ==
Line 263: Line 217:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 17|Solution]]
+
[[2002 AMC 12P Problems/Problem 17|Solution]]
  
 
== Problem 18 ==
 
== Problem 18 ==
Line 299: Line 253:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 18|Solution]]
+
[[2002 AMC 12P Problems/Problem 18|Solution]]
  
 
== Problem 19 ==
 
== Problem 19 ==
Line 317: Line 271:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 19|Solution]]
+
[[2002 AMC 12P Problems/Problem 19|Solution]]
  
 
== Problem 20 ==
 
== Problem 20 ==
Line 335: Line 289:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 20|Solution]]
+
[[2002 AMC 12P Problems/Problem 20|Solution]]
  
 
== Problem 21 ==
 
== Problem 21 ==
Line 383: Line 337:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 22|Solution]]
+
[[2002 AMC 12P Problems/Problem 22|Solution]]
  
 
== Problem 23 ==
 
== Problem 23 ==
Line 401: Line 355:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 23|Solution]]
+
[[2002 AMC 12P Problems/Problem 23|Solution]]
  
 
== Problem 24 ==
 
== Problem 24 ==
Line 419: Line 373:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 24|Solution]]
+
[[2002 AMC 12P Problems/Problem 24|Solution]]
  
 
== Problem 25 ==
 
== Problem 25 ==
Line 437: Line 391:
 
</math>
 
</math>
  
[[2001 AMC 12 Problems/Problem 25|Solution]]
+
[[2002 AMC 12P Problems/Problem 25|Solution]]
  
 
== See also ==
 
== See also ==
Line 445: Line 399:
 
* [[AMC 12]]
 
* [[AMC 12]]
 
* [[AMC 12 Problems and Solutions]]
 
* [[AMC 12 Problems and Solutions]]
* [[2001 AMC 12]]
+
* [[2002 AMC 12]]
 
* [[Mathematics competition resources]]
 
* [[Mathematics competition resources]]
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 21:11, 29 December 2023

2002 AMC 12P (Answer Key)
Printable versions: WikiAoPS ResourcesPDF

Instructions

  1. 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.
  2. 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.
  3. No aids are permitted other than scratch paper, graph paper, ruler, compass, protractor and erasers (and calculators that are accepted for use on the test if before 2006. No problems on the test will require the use of a calculator).
  4. Figures are not necessarily drawn to scale.
  5. 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

Which of the following numbers is a perfect square?

$\text{(A)}\ 4^5 5^5 6^6 \qquad \text{(B)}\ 4^4 5^6 6^5 \qquad \text{(C)}\ 4^5 5^4 6^6 \qquad\text{(D)} 4^6 5^4 6^5 \qquad \text{(E)}\ 4^6 5^5 6^4$

Solution

Problem 2

The function $f$ is given by the table

If $u_0=4$ and $u_{n+1} = f(u_n)$ for $n>=0$, find $u_2002$

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

Solution

Problem 3

The dimensions of a rectangular box in inches are all positive integers and the volume of the box is $2002$ in^3. Find the minimum possible sum of the three dimensions.

$\text{(A)}\ \36\qquad \text{(B)}\ \38\qquad \text{(C)}\ \42\qquad \text{(D)}\ \44\qquad \text{(E)}\ \92$ (Error compiling LaTeX. Unknown error_msg)

Solution

Problem 4

Let $a$ and $b$ be distinct real numbers for which \[\frac{a}{b} + \frac{a+10b}{b+10a} = 2.\] Find $\frac{a}{b}$

$\text{(A)}\ 0.4\qquad \text{(B)}\ 0.5\qquad \text{(C)}\ 0.6\qquad \text{(D)}\ 0.7\qquad \text{(E)}\ 0.8$

Solution

Problem 5

For how many positive integers $m$ is \[\frac{2002}{m^2 -2}\]

$\text{(A)}\ one\qquad \text{(B)}\ two\qquad \text{(C)}\ three\qquad \text{(D)}\ four\qquad \text{(E)}\ five$

Solution

Problem 6

Participation in the local soccer league this year is $10%$ (Error compiling LaTeX. Unknown error_msg) higher than last year. The number of males increased by $5%$ (Error compiling LaTeX. Unknown error_msg) and the number of females increased by $20%$ (Error compiling LaTeX. Unknown error_msg). What fraction of the soccer league is now female?

$\text{(A)}\ \frac{1}{3}\qquad \text{(B)}\ \frac{4}{11}\qquad \text{(C)}\ \frac{2}{5}\qquad \text{(D)}\ \frac{4}{9}\qquad \text{(E)}\ \frac{1}{2}$

Solution

Problem 7

How many three-digit numbers have at least one 2 and at least one 3?

$\text{(A) }\52\qquad \text{(B) }\54\qquad \text{(C) }\56\qquad \text{(D) }\58\qquad \text{(E) }\60$ (Error compiling LaTeX. Unknown error_msg)

Solution

Problem 8

Let $AB$ be a segment of length $26$, and let points $C$ and $D$ be located on $AB$ such that $AC=1$ and $AD=8$. Let $E$ and $F$ be points on one of the semicircles with diameter $AB$ for which $EC$ and $FD$ are perpendicular to $AB$. Find $EF.$

$\text{(A) }\5\qquad \text{(B) }\5\sqrt{2}\qquad \text{(C) }\7\qquad \text{(D) }\7\sqrt{2}\qquad \text{(E) }\12$ (Error compiling LaTeX. Unknown error_msg)

Solution

Problem 9

Two walls and the ceiling of a room meet at right angles at point $P.$ A fly is in the air one meter from one wall, eight meters from the other wall, and nine meters from point $P$. How many meters is the fly from the ceiling?

$\text{(A)}\ \sqrt{13} \qquad \text{(B)}\ 2 \qquad \text{(C)}\ \frac52 \qquad \text{(D)}\ 3 \qquad \text{(E)}\ \frac{18}5$

Solution

Problem 10

Let $f_n (x) = sin^n x + cos^n x.$ For how many $x$ in $[0,π]$ (Error compiling LaTeX. Unknown error_msg) is it true that

$\text{(A) }2 \qquad \text{(B) }4  \qquad \text{(C) }6 \qquad \text{(D) }8 \qquad \text{(E) }more than 8$

Solution

Problem 11

Let $t_n = \frac{n(n+1)}{2}$ be the $n$th triangular number. Find

\[\frac{1}{t_1} + \frac{1}{t_2} + \frac{1}{t_3} + ... + \frac{1}{t_2002}\]

$\text{(A) }\frac {4003}{2003} \qquad \text{(B) }\frac {2001}{1001} \qquad \text{(C) }\frac {4004}{2003} \qquad \text{(D) }\frac {4001}{2001} \qquad \text{(E) }2$

Solution

Problem 12

What is the maximum value of $n$ for which there is a set of distinct positive integers $k_1, k_2, ... k_n$ for which

$$ (Error compiling LaTeX. Unknown error_msg)k^2_1 $\text{(A) }768 \qquad \text{(B) }801 \qquad \text{(C) }934 \qquad \text{(D) }1067 \qquad \text{(E) }1167$

Solution

Problem 13

The parabola with equation $y=ax^2+bx+c$ and vertex $(h,k)$ is reflected about the line $y=k$. This results in the parabola with equation $y=dx^2+ex+f$. Which of the following equals $a+b+c+d+e+f$?

$\text{(A) }2b \qquad \text{(B) }2c \qquad \text{(C) }2a+2b \qquad \text{(D) }2h \qquad \text{(E) }2k$

Solution

Problem 14

Given the nine-sided regular polygon $A_1 A_2 A_3 A_4 A_5 A_6 A_7 A_8 A_9$, how many distinct equilateral triangles in the plane of the polygon have at least two vertices in the set $\{A_1,A_2,\dots,A_9\}$?

$\text{(A) }30 \qquad \text{(B) }36 \qquad \text{(C) }63 \qquad \text{(D) }66 \qquad \text{(E) }72$

Solution

Problem 15

An insect lives on the surface of a regular tetrahedron with edges of length 1. It wishes to travel on the surface of the tetrahedron from the midpoint of one edge to the midpoint of the opposite edge. What is the length of the shortest such trip? (Note: Two edges of a tetrahedron are opposite if they have no common endpoint.)

$\text{(A) }\frac {1}{2} \sqrt {3} \qquad \text{(B) }1 \qquad \text{(C) }\sqrt {2} \qquad \text{(D) }\frac {3}{2} \qquad \text{(E) }2$

Solution

Problem 16

A spider has one sock and one shoe for each of its eight legs. In how many different orders can the spider put on its socks and shoes, assuming that, on each leg, the sock must be put on before the shoe?

$\text{(A) }8! \qquad \text{(B) }2^8 \cdot 8! \qquad \text{(C) }(8!)^2 \qquad \text{(D) }\frac {16!}{2^8} \qquad \text{(E) }16!$

Solution

Problem 17

A point $P$ is selected at random from the interior of the pentagon with vertices $A = (0,2)$, $B = (4,0)$, $C = (2 \pi + 1, 0)$, $D = (2 \pi + 1,4)$, and $E=(0,4)$. What is the probability that $\angle APB$ is obtuse?

$\text{(A) }\frac {1}{5} \qquad \text{(B) }\frac {1}{4} \qquad \text{(C) }\frac {5}{16} \qquad \text{(D) }\frac {3}{8} \qquad \text{(E) }\frac {1}{2}$

Solution

Problem 18

A circle centered at $A$ with a radius of 1 and a circle centered at $B$ with a radius of 4 are externally tangent. A third circle is tangent to the first two and to one of their common external tangents as shown. The radius of the third circle is

[asy] unitsize(0.75cm); pair A=(0,1), B=(4,4); dot(A); dot(B); draw( circle(A,1) ); draw( circle(B,4) ); draw( (-1.5,0)--(8.5,0) ); draw( A -- (A+(-1,0)) ); label("$1$", A -- (A+(-1,0)), N ); draw( B -- (B+(4,0)) ); label("$4$", B -- (B+(4,0)), N ); label("$A$",A,E); label("$B$",B,W);  filldraw( circle( (12/9,4/9), 4/9 ), lightgray, black ); dot( (12/9,4/9) ); [/asy]

$\text{(A) }\frac {1}{3} \qquad \text{(B) }\frac {2}{5} \qquad \text{(C) }\frac {5}{12} \qquad \text{(D) }\frac {4}{9} \qquad \text{(E) }\frac {1}{2}$

Solution

Problem 19

The polynomial $P(x)=x^3+ax^2+bx+c$ has the property that the mean of its zeros, the product of its zeros, and the sum of its coefficients are all equal. If the $y$-intercept of the graph of $y=P(x)$ is 2, what is $b$?

$\text{(A) }-11 \qquad \text{(B) }-10 \qquad \text{(C) }-9 \qquad \text{(D) }1 \qquad \text{(E) }5$

Solution

Problem 20

Points $A = (3,9)$, $B = (1,1)$, $C = (5,3)$, and $D=(a,b)$ lie in the first quadrant and are the vertices of quadrilateral $ABCD$. The quadrilateral formed by joining the midpoints of $\overline{AB}$, $\overline{BC}$, $\overline{CD}$, and $\overline{DA}$ is a square. What is the sum of the coordinates of point $D$?

$\text{(A) }7 \qquad \text{(B) }9 \qquad \text{(C) }10 \qquad \text{(D) }12 \qquad \text{(E) }16$

Solution

Problem 21

Four positive integers $a$, $b$, $c$, and $d$ have a product of $8!$ and satisfy:

\begin{align*} ab + a + b & = 524 \\  bc + b + c & = 146 \\  cd + c + d & = 104 \end{align*}

What is $a-d$?

$\text{(A) }4 \qquad \text{(B) }6 \qquad \text{(C) }8 \qquad \text{(D) }10 \qquad \text{(E) }12$

Solution

Problem 22

In rectangle $ABCD$, points $F$ and $G$ lie on $AB$ so that $AF=FG=GB$ and $E$ is the midpoint of $\overline{DC}$. Also, $\overline{AC}$ intersects $\overline{EF}$ at $H$ and $\overline{EG}$ at $J$. The area of the rectangle $ABCD$ is $70$. Find the area of triangle $EHJ$.

$\text{(A) }\frac {5}{2} \qquad \text{(B) }\frac {35}{12} \qquad \text{(C) }3 \qquad \text{(D) }\frac {7}{2} \qquad \text{(E) }\frac {35}{8}$

Solution

Problem 23

A polynomial of degree four with leading coefficient 1 and integer coefficients has two real zeros, both of which are integers. Which of the following can also be a zero of the polynomial?

$\text{(A) }\frac {1 + i \sqrt {11}}{2} \qquad \text{(B) }\frac {1 + i}{2} \qquad \text{(C) }\frac {1}{2} + i \qquad \text{(D) }1 + \frac {i}{2} \qquad \text{(E) }\frac {1 + i \sqrt {13}}{2}$

Solution

Problem 24

In $\triangle ABC$, $\angle ABC=45^\circ$. Point $D$ is on $\overline{BC}$ so that $2\cdot BD=CD$ and $\angle DAB=15^\circ$. Find $\angle ACB$.

$\text{(A) }54^\circ \qquad \text{(B) }60^\circ \qquad \text{(C) }72^\circ \qquad \text{(D) }75^\circ \qquad \text{(E) }90^\circ$

Solution

Problem 25

Consider sequences of positive real numbers of the form $x, 2000, y, \dots$ in which every term after the first is 1 less than the product of its two immediate neighbors. For how many different values of $x$ does the term 2001 appear somewhere in the sequence?

$\text{(A) }1 \qquad \text{(B) }2 \qquad \text{(C) }3 \qquad \text{(D) }4 \qquad \text{(E) more than }4$

Solution

See also

2001 AMC 12 (ProblemsAnswer KeyResources)
Preceded by
2000 AMC 12 Problems
Followed by
2002 AMC 12A Problems
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
All AMC 12 Problems and Solutions

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