Difference between revisions of "2001 AMC 10 Problems"

Latest revision as of 15:25, 2 June 2022

2001 AMC 10 (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

The median of the list $n, n + 3, n + 4, n + 5, n + 6, n + 8, n + 10, n + 12, n + 15$ is $10$ . What is the mean?

$\textbf{(A) } 4 \qquad\textbf{(B) } 6 \qquad\textbf{(C) } 7 \qquad\textbf{(D) } 10 \qquad\textbf{(E) } 11$

Solution

Problem 2

A number $x$ is $2$ more than the product of its reciprocal and its additive inverse. In which interval does the number lie?

$\textbf{(A) } -4\leq x\leq -2 \qquad\textbf{(B) } -2<x\leq 0 \qquad\textbf{(C) } 0<x\leq 2 \qquad\textbf{(D) } 2<x\leq 4 \qquad\textbf{(E) } 4<x\leq 6$

Solution

Problem 3

The sum of two numbers is $S$ . Suppose $3$ is added to each number and then each of the resulting numbers is doubled. What is the sum of the final two numbers?

$\textbf{(A) } 2S+3 \qquad\textbf{(B) } 3S+2 \qquad\textbf{(C) } 3S+6 \qquad\textbf{(D) } 2S+6 \qquad\textbf{(E) } 2S+12$

Solution

Problem 4

What is the maximum number for the possible points of intersection of a circle and a triangle?

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

Solution

Problem 5

How many of the twelve pentominoes pictured below have at least one line of reflectional symmetry?

$[asy] unitsize(5mm); defaultpen(linewidth(1pt)); draw(shift(2,0)*unitsquare); draw(shift(2,1)*unitsquare); draw(shift(2,2)*unitsquare); draw(shift(1,2)*unitsquare); draw(shift(0,2)*unitsquare); draw(shift(2,4)*unitsquare); draw(shift(2,5)*unitsquare); draw(shift(2,6)*unitsquare); draw(shift(1,5)*unitsquare); draw(shift(0,5)*unitsquare); draw(shift(4,8)*unitsquare); draw(shift(3,8)*unitsquare); draw(shift(2,8)*unitsquare); draw(shift(1,8)*unitsquare); draw(shift(0,8)*unitsquare); draw(shift(6,8)*unitsquare); draw(shift(7,8)*unitsquare); draw(shift(8,8)*unitsquare); draw(shift(9,8)*unitsquare); draw(shift(9,9)*unitsquare); draw(shift(6,5)*unitsquare); draw(shift(7,5)*unitsquare); draw(shift(8,5)*unitsquare); draw(shift(7,6)*unitsquare); draw(shift(7,4)*unitsquare); draw(shift(6,1)*unitsquare); draw(shift(7,1)*unitsquare); draw(shift(8,1)*unitsquare); draw(shift(6,0)*unitsquare); draw(shift(7,2)*unitsquare); draw(shift(11,8)*unitsquare); draw(shift(12,8)*unitsquare); draw(shift(13,8)*unitsquare); draw(shift(14,8)*unitsquare); draw(shift(13,9)*unitsquare); draw(shift(11,5)*unitsquare); draw(shift(12,5)*unitsquare); draw(shift(13,5)*unitsquare); draw(shift(11,6)*unitsquare); draw(shift(13,4)*unitsquare); draw(shift(11,1)*unitsquare); draw(shift(12,1)*unitsquare); draw(shift(13,1)*unitsquare); draw(shift(13,2)*unitsquare); draw(shift(14,2)*unitsquare); draw(shift(16,8)*unitsquare); draw(shift(17,8)*unitsquare); draw(shift(18,8)*unitsquare); draw(shift(17,9)*unitsquare); draw(shift(18,9)*unitsquare); draw(shift(16,5)*unitsquare); draw(shift(17,6)*unitsquare); draw(shift(18,5)*unitsquare); draw(shift(16,6)*unitsquare); draw(shift(18,6)*unitsquare); draw(shift(16,0)*unitsquare); draw(shift(17,0)*unitsquare); draw(shift(17,1)*unitsquare); draw(shift(18,1)*unitsquare); draw(shift(18,2)*unitsquare);[/asy]$

$\textbf{(A) } 3 \qquad\textbf{(B) } 4 \qquad\textbf{(C) } 5 \qquad\textbf{(D) } 6 \qquad\textbf{(E) } 7$

Solution

Problem 6

Let $P(n)$ and $S(n)$ denote the product and the sum, respectively, of the digits of the integer $n$ . For example, $P(23) = 6$ and $S(23) = 5$ . Suppose $N$ is a two-digit number such that $N = P(N)+S(N)$ . What is the units digit of $N$ ?

$\textbf{(A) } 2 \qquad\textbf{(B) } 3 \qquad\textbf{(C) } 6 \qquad\textbf{(D) } 8 \qquad\textbf{(E) } 9$

Solution

Problem 7

When the decimal point of a certain positive decimal number is moved four places to the right, the new number is four times the reciprocal of the original number. What is the original number?

$\textbf{(A) } 0.0002 \qquad\textbf{(B) } 0.002 \qquad\textbf{(C) } 0.02 \qquad\textbf{(D) } 0.2 \qquad\textbf{(E) } 2$

Solution

Problem 8

Wanda, Darren, Beatrice, and Chi are tutors in the school math lab. Their schedule is as follows: Darren works every third school day, Wanda works every fourth school day, Beatrice works every sixth school day, and Chi works every seventh school day. Today they are all working in the math lab. In how many school days from today will they next be together tutoring in the lab?

$\textbf{(A) } 42 \qquad\textbf{(B) } 84 \qquad\textbf{(C) } 126 \qquad\textbf{(D) } 178 \qquad\textbf{(E) } 252$

Solution

Problem 9

The state income tax where Kristin lives is levied at the rate of $p\%$ of the first $\textdollar 28000$ of annual income plus $(p + 2)\%$ of any amount above $\textdollar 28000$ . Kristin noticed that the state income tax she paid amounted to $(p + 0.25)\%$ of her annual income. What was her annual income?

$\textbf{(A) } \textdollar 28,000\qquad\textbf{(B) } \textdollar 32,000\qquad\textbf{(C) }\textdollar 35,000\qquad\textbf{(D) } \textdollar 42,000\qquad\textbf{(E) } \textdollar 56,000$

Solution

Problem 10

If $x$ , $y$ , and $z$ are positive with $xy = 24$ , $xz = 48$ , and $yz = 72$ , then $x + y + z$ is

$\textbf{(A) }18\qquad\textbf{(B) }19\qquad\textbf{(C) }20\qquad\textbf{(D) }22\qquad\textbf{(E) }24$

Solution

Problem 11

Consider the dark square in an array of unit squares, part of which is shown. The ﬁrst ring of squares around this center square contains $8$ unit squares. The second ring contains $16$ unit squares. If we continue this process, the number of unit squares in the $100^\text{th}$ ring is

$[asy] unitsize(3mm); defaultpen(linewidth(1pt)); fill((2,2)--(2,7)--(7,7)--(7,2)--cycle, mediumgray); fill((3,3)--(6,3)--(6,6)--(3,6)--cycle, gray); fill((4,4)--(5,4)--(5,5)--(4,5)--cycle, black); for(real i=0; i<=9; ++i) { draw((i,0)--(i,9)); draw((0,i)--(9,i)); }[/asy]$

$\textbf{(A)}\ 396 \qquad \textbf{(B)}\ 404 \qquad \textbf{(C)}\ 800 \qquad \textbf{(D)}\ 10,\!000 \qquad \textbf{(E)}\ 10,\!404$

Solution

Problem 12

Suppose that $n$ is the product of three consecutive integers and that $n$ is divisible by $7$ . Which of the following is not necessarily a divisor of $n$ ?

$\textbf{(A)}\ 6 \qquad \textbf{(B)}\ 14 \qquad \textbf{(C)}\ 21 \qquad \textbf{(D)}\ 28 \qquad \textbf{(E)}\ 42$

Solution

Problem 13

A telephone number has the form $ABC - DEF - GHIJ$ , where each letter represents a different digit. The digits in each part of the numbers are in decreasing order; that is, $A > B > C$ , $D > E > F$ , and $G > H > I > J$ . Furthermore, $D$ , $E$ , and $F$ are consecutive even digits; $G$ , $H$ , $I$ , and $J$ are consecutive odd digits; and $A + B + C = 9$ . Find $A$ .

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

Solution

Problem 14

A charity sells $140$ benefit tickets for a total of $\textdollar2001$ . 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?

$\text{(A) } \textdollar 782 \qquad \text{(B) } \textdollar 986 \qquad \text{(C) } \textdollar 1158 \qquad \text{(D) } \textdollar 1219 \qquad \text{(E) }\ \textdollar 1449$

Solution

Problem 15

A street has parallel curbs $40$ feet apart. A crosswalk bounded by two parallel stripes crosses the street at an angle. The length of the curb between the stripes is $15$ feet and each stripe is $50$ feet long. Find the distance, in feet, between the stripes.

$\textbf{(A)}\ 9 \qquad \textbf{(B)}\ 10 \qquad \textbf{(C)}\ 12 \qquad \textbf{(D)}\ 15 \qquad \textbf{(E)}\ 25$

Solution

Problem 16

The mean of three numbers is $10$ more than the least of the numbers and $15$ less than the greatest. The median of the three numbers is $5$ . What is their sum?

$\textbf{(A)} \ 5 \qquad \textbf{(B)} \ 20 \qquad \textbf{(C)} \ 25 \qquad \textbf{(D)} \ 30 \qquad \textbf{(E)} \ 36$

Solution

Problem 17

Which of the cones listed below can be formed from a $252^\circ$ sector of a circle of radius $10$ by aligning the two straight sides?

$[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]$

$\textbf{(A) } \text{A cone with slant height of 10 and radius 6}$

$\textbf{(B) } \text{A cone with height of 10 and radius 6}$

$\textbf{(C) } \text{A cone with slant height of 10 and radius 7}$

$\textbf{(D) } \text{A cone with height of 10 and radius 7}$

$\textbf{(E) } \text{A cone with slant height of 10 and radius 8}$

Solution

Problem 18

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

$[asy] unitsize(3mm); defaultpen(linewidth(0.8pt)); path p1=(0,0)--(3,0)--(3,3)--(0,3)--(0,0); path p2=(0,1)--(1,1)--(1,0); path p3=(2,0)--(2,1)--(3,1); path p4=(3,2)--(2,2)--(2,3); path p5=(1,3)--(1,2)--(0,2); path p6=(1,1)--(2,2); path p7=(2,1)--(1,2); path[] p=p1^^p2^^p3^^p4^^p5^^p6^^p7; for(int i=0; i<3; ++i) { for(int j=0; j<3; ++j) { draw(shift(3*i,3*j)*p); } }[/asy]$

$\textbf{(A)} \ 50 \qquad \textbf{(B)} \ 52 \qquad \textbf{(C)} \ 54 \qquad \textbf{(D)} \ 56 \qquad \textbf{(E)} \ 58 \qquad$

Solution

Problem 19

Pat wants to buy four donuts from an ample supply of three types of donuts: glazed, chocolate, and powdered. How many different selections are possible?

$\textbf{(A)}\ 6 \qquad \textbf{(B)}\ 9 \qquad \textbf{(C)}\ 12 \qquad \textbf{(D)}\ 15 \qquad \textbf{(E)}\ 18$

Solution

Problem 20

A regular octagon is formed by cutting an isosceles right triangle from each of the corners of a square with sides of length $2000$ . What is the length of each side of the octagon?

$\textbf{(A) } \frac{1}{3}(2000) \qquad \textbf{(B) } {2000(\sqrt{2}-1)} \qquad \textbf{(C) } {2000(2-\sqrt{2})} \qquad \textbf{(D) } {1000} \qquad \textbf{(E) } {1000\sqrt{2}}$

Solution

Problem 21

A right circular cylinder with its diameter equal to its height is inscribed in a right circular cone. The cone has diameter $10$ and altitude $12$ , and the axes of the cylinder and cone coincide. Find the radius of the cylinder.

$\textbf{(A)}\ \frac{8}3\qquad\textbf{(B)}\ \frac{30}{11}\qquad\textbf{(C)}\ 3\qquad\textbf{(D)}\ \frac{25}{8}\qquad\textbf{(E)}\ \frac{7}{2}$

Solution

Problem 22

In the magic square shown, the sums of the numbers in each row, column, and diagonal are the same. Five of these numbers are represented by $v$ , $w$ , $x$ , $y$ , and $z$ . Find $y + z$ .

$[asy] unitsize(10mm); defaultpen(linewidth(1pt)); for(int i=0; i<=3; ++i) { draw((0,i)--(3,i)); draw((i,0)--(i,3)); } label("$25$",(0.5,0.5)); label("$z$",(1.5,0.5)); label("$21$",(2.5,0.5)); label("$18$",(0.5,1.5)); label("$x$",(1.5,1.5)); label("$y$",(2.5,1.5)); label("$v$",(0.5,2.5)); label("$24$",(1.5,2.5)); label("$w$",(2.5,2.5)); [/asy]$

$\textbf{(A)}\ 43 \qquad \textbf{(B)}\ 44 \qquad \textbf{(C)}\ 45 \qquad \textbf{(D)}\ 46 \qquad \textbf{(E)}\ 47$

Solution

Problem 23

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?

$\textbf{(A)}\ \frac{3}{10}\qquad\textbf{(B)}\ \frac{2}{5}\qquad\textbf{(C)}\ \frac{1}{2}\qquad\textbf{(D)}\ \frac{3}{5}\qquad\textbf{(E)}\ \frac{7}{10}$

Solution

Problem 24

In trapezoid $ABCD$ , $\overline{AB}$ and $\overline{CD}$ are perpendicular to $\overline{AD}$ , with $AB+CD=BC$ , $AB<CD$ , and $AD=7$ . What is $AB\cdot CD$ ?

$\textbf{(A)}\ 12 \qquad \textbf{(B)}\ 12.25 \qquad \textbf{(C)}\ 12.5 \qquad \textbf{(D)}\ 12.75 \qquad \textbf{(E)}\ 13$

Solution

Problem 25

How many positive integers not exceeding $2001$ are multiples of $3$ or $4$ but not $5$ ?

$\textbf{(A)}\ 768 \qquad \textbf{(B)}\ 801 \qquad \textbf{(C)}\ 934 \qquad \textbf{(D)}\ 1067 \qquad \textbf{(E)}\ 1167$

Solution

2001 AMC 10 (Problems • Answer Key • Resources)
Preceded by 2000 AMC 10	Followed by 2002 AMC 10A
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All AMC 10 Problems and Solutions

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Difference between revisions of "2001 AMC 10 Problems"

Latest revision as of 15:25, 2 June 2022

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=2001|ab=}}
 ==Problem 1==
@@ Line 4: / Line 5: @@
 is <math>10</math>. What is the mean?
-<math>\mathrm{(A)}\ 4 \qquad\mathrm{(B)}\ 6 \qquad\mathrm{(C)}\ 7 \qquad\mathrm{(D)}\ 10 \qquad\mathrm{(E)}\ 11</math>
+<math>\textbf{(A) } 4 \qquad\textbf{(B) } 6 \qquad\textbf{(C) } 7 \qquad\textbf{(D) } 10 \qquad\textbf{(E) } 11</math>
+[[2001 AMC 10 Problems/Problem 1|Solution]]
 ==Problem 2==
 A number <math>x</math> is <math>2</math> more than the product of its reciprocal and its additive inverse. In which interval does the number lie?
-<math>\mathrm{(A)}\ -4\leq x\leq -2 \qquad\mathrm{(B)}\ -2<x\leq 0 \qquad\mathrm{(C)}\ 0<x\leq 2</math>
+<math>\textbf{(A) }  -4\leq x\leq -2 \qquad\textbf{(B) } -2<x\leq 0 \qquad\textbf{(C) } 0<x\leq 2 \qquad\textbf{(D) } 2<x\leq 4 \qquad\textbf{(E) } 4<x\leq 6</math>
-<math>\mathrm{(D)}\ 2<x\leq 4 \qquad\mathrm{(E)}\ 4<x\leq 6</math>
+[[2001 AMC 10 Problems/Problem 2|Solution]]
 ==Problem 3==
@@ Line 17: / Line 20: @@
 The sum of two numbers is <math>S</math>. Suppose <math>3</math> is added to each number and then each of the resulting numbers is doubled. What is the sum of the final two numbers?
-<math>\mathrm{(A)}\ 2S+3 \qquad\mathrm{(B)}\ 3S+2 \qquad\mathrm{(C)}\ 3S+6 \qquad\mathrm{(D)}\ 2S+6 \qquad\mathrm{(E)}\ 2S+12</math>
+<math>\textbf{(A) } 2S+3 \qquad\textbf{(B) } 3S+2 \qquad\textbf{(C) } 3S+6 \qquad\textbf{(D) } 2S+6 \qquad\textbf{(E) } 2S+12</math>
+[[2001 AMC 12 Problems/Problem 1|Solution]]
 ==Problem 4==
@@ Line 23: / Line 28: @@
 What is the maximum number for the possible points of intersection of a circle and a triangle?
-<math>\mathrm{(A)}\ 2 \qquad\mathrm{(B)}\ 3 \qquad\mathrm{(C)}\ 4 \qquad\mathrm{(D)}\ 5 \qquad\mathrm{(E)}\ 6</math>
+<math>\textbf{(A) } 2 \qquad\textbf{(B) } 3 \qquad\textbf{(C) } 4 \qquad\textbf{(D) } 5 \qquad\textbf{(E) } 6</math>
+[[2001 AMC 10 Problems/Problem 4|Solution]]
 ==Problem 5==
-How many of the twelve pentominoes pictured below have at least one line of
+How many of the twelve pentominoes pictured below have at least one line of reflectional symmetry?
-symmetry?
+<asy>
+unitsize(5mm);
+defaultpen(linewidth(1pt));
+draw(shift(2,0)*unitsquare);
+draw(shift(2,1)*unitsquare);
+draw(shift(2,2)*unitsquare);
+draw(shift(1,2)*unitsquare);
+draw(shift(0,2)*unitsquare);
+draw(shift(2,4)*unitsquare);
+draw(shift(2,5)*unitsquare);
+draw(shift(2,6)*unitsquare);
+draw(shift(1,5)*unitsquare);
+draw(shift(0,5)*unitsquare);
+draw(shift(4,8)*unitsquare);
+draw(shift(3,8)*unitsquare);
+draw(shift(2,8)*unitsquare);
+draw(shift(1,8)*unitsquare);
+draw(shift(0,8)*unitsquare);
+draw(shift(6,8)*unitsquare);
+draw(shift(7,8)*unitsquare);
+draw(shift(8,8)*unitsquare);
+draw(shift(9,8)*unitsquare);
+draw(shift(9,9)*unitsquare);
+draw(shift(6,5)*unitsquare);
+draw(shift(7,5)*unitsquare);
+draw(shift(8,5)*unitsquare);
+draw(shift(7,6)*unitsquare);
+draw(shift(7,4)*unitsquare);
+draw(shift(6,1)*unitsquare);
+draw(shift(7,1)*unitsquare);
+draw(shift(8,1)*unitsquare);
+draw(shift(6,0)*unitsquare);
+draw(shift(7,2)*unitsquare);
+draw(shift(11,8)*unitsquare);
+draw(shift(12,8)*unitsquare);
+draw(shift(13,8)*unitsquare);
+draw(shift(14,8)*unitsquare);
+draw(shift(13,9)*unitsquare);
+draw(shift(11,5)*unitsquare);
+draw(shift(12,5)*unitsquare);
+draw(shift(13,5)*unitsquare);
+draw(shift(11,6)*unitsquare);
+draw(shift(13,4)*unitsquare);
+draw(shift(11,1)*unitsquare);
+draw(shift(12,1)*unitsquare);
+draw(shift(13,1)*unitsquare);
+draw(shift(13,2)*unitsquare);
+draw(shift(14,2)*unitsquare);
+draw(shift(16,8)*unitsquare);
+draw(shift(17,8)*unitsquare);
+draw(shift(18,8)*unitsquare);
+draw(shift(17,9)*unitsquare);
+draw(shift(18,9)*unitsquare);
+draw(shift(16,5)*unitsquare);
+draw(shift(17,6)*unitsquare);
+draw(shift(18,5)*unitsquare);
+draw(shift(16,6)*unitsquare);
+draw(shift(18,6)*unitsquare);
+draw(shift(16,0)*unitsquare);
+draw(shift(17,0)*unitsquare);
+draw(shift(17,1)*unitsquare);
+draw(shift(18,1)*unitsquare);
+draw(shift(18,2)*unitsquare);</asy>
-<math>\mathrm{(A)}\ 3 \qquad\mathrm{(B)}\ 2 \qquad\mathrm{(C)}\ 5 \qquad\mathrm{(D)}\ 6 \qquad\mathrm{(E)}\ 7</math>
+<math>\textbf{(A) } 3 \qquad\textbf{(B) } 4 \qquad\textbf{(C) } 5 \qquad\textbf{(D) } 6 \qquad\textbf{(E) } 7</math>
+[[2001 AMC 10 Problems/Problem 5|Solution]]
 ==Problem 6==
@@ Line 38: / Line 110: @@
 two-digit number such that <math>N = P(N)+S(N)</math>. What is the units digit of <math>N</math>?
-<math>\mathrm{(A)}\ 2 \qquad\mathrm{(B)}\ 3 \qquad\mathrm{(C)}\ 6 \qquad\mathrm{(D)}\ 8 \qquad\mathrm{(E)}\ 9</math>
+<math>\textbf{(A) } 2 \qquad\textbf{(B) } 3 \qquad\textbf{(C) } 6 \qquad\textbf{(D) } 8 \qquad\textbf{(E) } 9</math>
+[[2001 AMC 12 Problems/Problem 2|Solution]]
 ==Problem 7==
@@ Line 46: / Line 120: @@
 number. What is the original number?
-<math>\mathrm{(A)}\ 0.0002 \qquad\mathrm{(B)}\ 0.002 \qquad\mathrm{(C)}\ 0.02 \qquad\mathrm{(D)}\ 0.2 \qquad\mathrm{(E)}\ 2</math>
+<math>\textbf{(A) } 0.0002 \qquad\textbf{(B) } 0.002 \qquad\textbf{(C) } 0.02 \qquad\textbf{(D) } 0.2 \qquad\textbf{(E) } 2</math>
+[[2001 AMC 10 Problems/Problem 7|Solution]]
 ==Problem 8==
@@ Line 56: / Line 132: @@
 many school days from today will they next be together tutoring in the lab?
-<math>\mathrm{(A)}\ 42 \qquad\mathrm{(B)}\ 84 \qquad\mathrm{(C)}\ 126 \qquad\mathrm{(D)}\ 178 \qquad\mathrm{(E)}\ 252</math>
+<math>\textbf{(A) } 42 \qquad\textbf{(B) } 84 \qquad\textbf{(C) } 126 \qquad\textbf{(D) } 178 \qquad\textbf{(E) } 252</math>
+[[2001 AMC 10 Problems/Problem 8|Solution]]
+== Problem 9 ==
+The state income tax where Kristin lives is levied at the rate of <math> p\% </math> of the first <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> \textbf{(A) } \textdollar 28,000\qquad\textbf{(B) } \textdollar 32,000\qquad\textbf{(C) }\textdollar 35,000\qquad\textbf{(D) } \textdollar 42,000\qquad\textbf{(E) } \textdollar 56,000 </math>
+[[2001 AMC 10 Problems/Problem 9|Solution]]
+== Problem 10 ==
+If <math>x</math>, <math>y</math>, and <math>z</math> are positive with <math>xy = 24</math>, <math>xz = 48</math>, and <math>yz = 72</math>, then <math>x + y + z</math> is
+<math>\textbf{(A) }18\qquad\textbf{(B) }19\qquad\textbf{(C) }20\qquad\textbf{(D) }22\qquad\textbf{(E) }24</math>
+[[2001 AMC 10 Problems/Problem 10|Solution]]
+== Problem 11 ==
+Consider the dark square in an array of unit squares, part of which is shown. The ﬁrst ring of squares around this center square contains <math> 8 </math> unit squares. The second ring contains <math> 16 </math> unit squares. If we continue this process, the number of unit squares in the <math> 100^\text{th} </math> ring is
+<asy>
+unitsize(3mm);
+defaultpen(linewidth(1pt));
+fill((2,2)--(2,7)--(7,7)--(7,2)--cycle, mediumgray);
+fill((3,3)--(6,3)--(6,6)--(3,6)--cycle, gray);
+fill((4,4)--(5,4)--(5,5)--(4,5)--cycle, black);
+for(real i=0; i<=9; ++i)
+{
+draw((i,0)--(i,9));
+draw((0,i)--(9,i));
+}</asy>
+<math>\textbf{(A)}\ 396 \qquad \textbf{(B)}\ 404 \qquad \textbf{(C)}\ 800 \qquad \textbf{(D)}\ 10,\!000 \qquad \textbf{(E)}\ 10,\!404</math>
+[[2001 AMC 10 Problems/Problem 11|Solution]]
+== Problem 12 ==
+Suppose that <math> n </math> is the product of three consecutive integers and that <math> n </math> is divisible by <math> 7 </math>. Which of the following is not necessarily a divisor of <math> n </math>?
+<math> \textbf{(A)}\ 6 \qquad \textbf{(B)}\ 14 \qquad \textbf{(C)}\ 21 \qquad \textbf{(D)}\ 28 \qquad \textbf{(E)}\ 42 </math>
+[[2001 AMC 10 Problems/Problem 12|Solution]]
+== Problem 13 ==
+A telephone number has the form <math> ABC - DEF - GHIJ </math>, where each letter represents a different digit. The digits in each part of the numbers 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>\textbf{(A)} \ 4 \qquad \textbf{(B)} \ 5 \qquad \textbf{(C)} \ 6 \qquad \textbf{(D)} \ 7 \qquad \textbf{(E)} \ 8</math>
+[[2001 AMC 12 Problems/Problem 6|Solution]]
+== Problem 14 ==
+A charity sells <math>140</math> benefit tickets for a total of <math>\textdollar2001</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?
+<math>\text{(A) } \textdollar 782 \qquad \text{(B) } \textdollar 986 \qquad \text{(C) } \textdollar 1158 \qquad \text{(D) } \textdollar 1219 \qquad \text{(E) }\ \textdollar 1449</math>
+[[2001 AMC 12 Problems/Problem 7|Solution]]
+== Problem 15 ==
+A street has parallel curbs <math> 40 </math> feet apart. A crosswalk bounded by two parallel stripes crosses the street at an angle. The length of the curb between the stripes is <math> 15 </math> feet and each stripe is <math> 50 </math> feet long. Find the distance, in feet, between the stripes.
+<math> \textbf{(A)}\ 9 \qquad \textbf{(B)}\ 10 \qquad \textbf{(C)}\ 12 \qquad \textbf{(D)}\ 15 \qquad \textbf{(E)}\ 25 </math>
+[[2001 AMC 10 Problems/Problem 15|Solution]]
+== Problem 16 ==
+The mean of three numbers is <math> 10 </math> more than the least of the numbers and <math> 15 </math> less than the greatest. The median of the three numbers is <math> 5 </math>. What is their sum?
+<math> \textbf{(A)} \ 5 \qquad \textbf{(B)} \ 20 \qquad \textbf{(C)} \ 25 \qquad \textbf{(D)} \ 30 \qquad \textbf{(E)} \ 36 </math>
+[[2001 AMC 12 Problems/Problem 4|Solution]]
+== Problem 17 ==
+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?
+<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> \textbf{(A) } \text{A cone with slant height of 10 and radius 6} </math>
+<math> \textbf{(B) } \text{A cone with height of 10 and radius 6} </math>
+<math> \textbf{(C) } \text{A cone with slant height of 10 and radius 7} </math>
+<math> \textbf{(D) } \text{A cone with height of 10 and radius 7} </math>
+<math> \textbf{(E) } \text{A cone with slant height of 10 and radius 8} </math>
+[[2001 AMC 12 Problems/Problem 8|Solution]]
+== Problem 18 ==
+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
+<asy>
+unitsize(3mm);
+defaultpen(linewidth(0.8pt));
+path p1=(0,0)--(3,0)--(3,3)--(0,3)--(0,0);
+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>
+<math> \textbf{(A)} \ 50 \qquad \textbf{(B)} \ 52 \qquad \textbf{(C)} \ 54 \qquad \textbf{(D)} \ 56 \qquad \textbf{(E)} \ 58 \qquad </math>
+[[2001 AMC 12 Problems/Problem 10|Solution]]
+== Problem 19==
+Pat wants to buy four donuts from an ample supply of three types of donuts: glazed, chocolate, and powdered. How many different selections are possible?
+<math> \textbf{(A)}\ 6 \qquad \textbf{(B)}\ 9 \qquad \textbf{(C)}\ 12 \qquad \textbf{(D)}\ 15 \qquad \textbf{(E)}\ 18 </math>
+[[2001 AMC 10 Problems/Problem 19|Solution]]
+== Problem 20 ==
+A regular octagon is formed by cutting an isosceles right triangle from each of the corners of a square with sides of length <math> 2000 </math>. What is the length of each side of the octagon?
+<math> \textbf{(A) } \frac{1}{3}(2000) \qquad \textbf{(B) } {2000(\sqrt{2}-1)} \qquad \textbf{(C) } {2000(2-\sqrt{2})}
+\qquad \textbf{(D) } {1000} \qquad \textbf{(E) } {1000\sqrt{2}} </math>
+[[2001 AMC 10 Problems/Problem 20|Solution]]
+== Problem 21 ==
-=== Solutions ===
+A right circular cylinder with its diameter equal to its height is inscribed in a right circular cone. The cone has diameter <math> 10 </math> and altitude <math> 12 </math>, and the axes of the cylinder and cone coincide. Find the radius of the cylinder.
-. The median is <math>n+6</math>, therefore <math>n=4</math>. Computation shows that the sum of all numbers is <math>99</math> and thus the mean is <math>99/9=11</math>.
+<math> \textbf{(A)}\ \frac{8}3\qquad\textbf{(B)}\ \frac{30}{11}\qquad\textbf{(C)}\ 3\qquad\textbf{(D)}\ \frac{25}{8}\qquad\textbf{(E)}\ \frac{7}{2} </math>
-. The reciprocal of <math>x</math> is <math>\frac 1x</math> and the additive inverse is <math>-x</math>. (Note that <math>x</math> must be non-zero to have a reciprocal.)
+[[2001 AMC 10 Problems/Problem 21|Solution]]
-The product of these two is <math>\frac 1x \cdot (-x) = -1</math>. Thus <math>x</math> is <math>2</math> more than <math>-1</math>. Therefore <math>x=1</math>.
-. The original two numbers are <math>x</math> and <math>y</math>, with <math>x+y=S</math>. The new two numbers are <math>2(x+3)</math> and <math>2(y+3)</math>. Their sum is
+==Problem 22==
-<math>2(x+3)+2(y+3)=2x+2y+12=2(x+y)+12 = 2S+12</math>.
+In the magic square shown, the sums of the numbers in each row, column, and diagonal are the same. Five of these numbers are represented by <math> v </math>, <math> w </math>, <math> x </math>, <math> y </math>, and <math> z </math>. Find <math> y + z </math>.
-. Each side of the triangle can only intersect the circle twice, so the maximum is at most 6. This can be achieved:
 <asy>
-unitsize(0.3cm);
+unitsize(10mm);
-draw( circle((0,-0.2),2.2) );
+defaultpen(linewidth(1pt));
-draw( (-2,-2)--(2,-2)--(0,3)--cycle );
+for(int i=0; i<=3; ++i)
+{
+draw((0,i)--(3,i));
+draw((i,0)--(i,3));
+}
+label("$25$",(0.5,0.5));
+label("$z$",(1.5,0.5));
+label("$21$",(2.5,0.5));
+label("$18$",(0.5,1.5));
+label("$x$",(1.5,1.5));
+label("$y$",(2.5,1.5));
+label("$v$",(0.5,2.5));
+label("$24$",(1.5,2.5));
+label("$w$",(2.5,2.5));
 </asy>
+<math> \textbf{(A)}\ 43 \qquad \textbf{(B)}\ 44 \qquad \textbf{(C)}\ 45 \qquad \textbf{(D)}\ 46 \qquad \textbf{(E)}\ 47 </math>
+[[2001 AMC 10 Problems/Problem 22|Solution]]
+==Problem 23==
+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?
+<math> \textbf{(A)}\ \frac{3}{10}\qquad\textbf{(B)}\ \frac{2}{5}\qquad\textbf{(C)}\ \frac{1}{2}\qquad\textbf{(D)}\ \frac{3}{5}\qquad\textbf{(E)}\ \frac{7}{10} </math>
+[[2001 AMC 12 Problems/Problem 11|Solution]]
+==Problem 24==
+In trapezoid <math> ABCD </math>, <math> \overline{AB} </math> and <math> \overline{CD} </math> are perpendicular to <math> \overline{AD} </math>, with <math> AB+CD=BC </math>, <math> AB<CD </math>, and <math> AD=7 </math>. What is <math> AB\cdot CD </math>?
+<math> \textbf{(A)}\ 12 \qquad \textbf{(B)}\ 12.25 \qquad \textbf{(C)}\ 12.5 \qquad \textbf{(D)}\ 12.75 \qquad \textbf{(E)}\ 13 </math>
+[[2001 AMC 10 Problems/Problem 24|Solution]]
+==Problem 25==
+How many positive integers not exceeding <math> 2001 </math> are multiples of <math> 3 </math> or <math> 4 </math> but not <math> 5 </math>?
+<math> \textbf{(A)}\ 768 \qquad \textbf{(B)}\ 801 \qquad \textbf{(C)}\ 934 \qquad \textbf{(D)}\ 1067 \qquad \textbf{(E)}\ 1167 </math>
+[[2001 AMC 12 Problems/Problem 12|Solution]]
+== See also ==
+{{AMC10 box|year=2001|before=[[2000 AMC 10 Problems|2000 AMC 10]]|after=[[2002 AMC 10A Problems|2002 AMC 10A]]}}
+* [[AMC 10]]
+* [[AMC 10 Problems and Solutions]]
+* [[Mathematics competition resources]]
+{{MAA Notice}}