2013 AMC 12A Problems
2013 AMC 12A (Answer Key) Printable versions: • AoPS Resources • PDF | ||
Instructions
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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 |
Contents
- 1 Problem 1
- 2 Problem 2
- 3 Problem 3
- 4 Problem 4
- 5 Problem 5
- 6 Problem 6
- 7 Problem 7
- 8 Problem 8
- 9 Problem 9
- 10 Problem 10
- 11 Problem 11
- 12 Problem 12
- 13 Problem 13
- 14 Problem 14
- 15 Problem 15
- 16 Problem 16
- 17 Problem 17
- 18 Problem 18
- 19 Problem 19
- 20 Problem 20
- 21 Problem 21
- 22 Problem 22
- 23 Problem 23
- 24 Problem 24
- 25 Problem 25
Problem 1
Square has side length
. Point
is on
, and the area of
is
. What is
?
Problem 2
A softball team played ten games, scoring , and
runs. They lost by one run in exactly five games. In each of the other games, they scored twice as many runs as their opponent. How many total runs did their opponents score?
Problem 3
A flower bouquet contains pink roses, red roses, pink carnations, and red carnations. One third of the pink flowers are roses, three fourths of the red flowers are carnations, and six tenths of the flowers are pink. What percent of the flowers are carnations?
Problem 4
What is the value of
Problem 5
Tom, Dorothy, and Sammy went on a vacation and agreed to split the costs evenly. During their trip Tom paid $, Dorothy paid $
, and Sammy paid $
. In order to share the costs equally, Tom gave Sammy
dollars, and Dorothy gave Sammy
dollars. What is
?
Problem 6
In a recent basketball game, Shenille attempted only three-point shots and two-point shots. She was successful on of her three-point shots and
of her two-point shots. Shenille attempted
shots. How many points did she score?
Problem 7
The sequence has the property that every term beginning with the third is the sum of the previous two. That is,
Suppose that
and
. What is
?
Problem 8
Given that and
are distinct nonzero real numbers such that
, what is
?
Problem 9
In ,
and
. Points
and
are on sides
,
, and
, respectively, such that
and
are parallel to
and
, respectively. What is the perimeter of parallelogram
?
Problem 10
Let be the set of positive integers
for which
has the repeating decimal representation
with
and
different digits. What is the sum of the elements of
?
Problem 11
Triangle is equilateral with
. Points
and
are on
and points
and
are on
such that both
and
are parallel to
. Furthermore, triangle
and trapezoids
and
all have the same perimeter. What is
?
Problem 12
The angles in a particular triangle are in arithmetic progression, and the side lengths are . The sum of the possible values of x equals
where
, and
are positive integers. What is
?
Problem 13
Let points and
. Quadrilateral
is cut into equal area pieces by a line passing through
. This line intersects
at point
, where these fractions are in lowest terms. What is
?
Problem 14
The sequence
,
,
,
,
is an arithmetic progression. What is ?
Problem 15
Rabbits Peter and Pauline have three offspring—Flopsie, Mopsie, and Cotton-tail. These five rabbits are to be distributed to four different pet stores so that no store gets both a parent and a child. It is not required that every store gets a rabbit. In how many different ways can this be done?
Problem 16
,
,
are three piles of rocks. The mean weight of the rocks in
is
pounds, the mean weight of the rocks in
is
pounds, the mean weight of the rocks in the combined piles
and
is
pounds, and the mean weight of the rocks in the combined piles
and
is
pounds. What is the greatest possible integer value for the mean in pounds of the rocks in the combined piles
and
?
Problem 17
A group of pirates agree to divide a treasure chest of gold coins among themselves as follows. The
pirate to take a share takes
of the coins that remain in the chest. The number of coins initially in the chest is the smallest number for which this arrangement will allow each pirate to receive a positive whole number of coins. How many coins doe the
pirate receive?
Problem 18
Six spheres of radius are positioned so that their centers are at the vertices of a regular hexagon of side length
. The xis spheres are internally tangent to a larger sphere whose center is the center of the hexagon. An eighth sphere is externally tangent to the six smaller spheres and internally tangent to the larger sphere. What is the radius of this eighth sphere?
Problem 19
In ,
, and
. A cricle with center
and radius
intersects
at points
and
. Moreover
and
have integer lengths. What is
?
Problem 20
Let be the set
. For
, define
to mean that either
or
. How many ordered triples
of elements of
have the property that
,
, and
?
Problem 21
Consider . Which of the following intervals contains
?
Problem 22
A palindrome is a nonnegatvie integer number that reads the same forwards and backwards when written in base 10 with no leading zeros. A 6-digit palindrome is chosen uniformly at random. What is the probability that
is also a palindrome?
Problem 23
is a square of side length
. Point
is on
such that
. The square region bounded by
is rotated
counterclockwise with center
, sweeping out a region whose area is
, where
,
, and
are positive integers and
. What is
?
Problem 24
Three distinct segments are chosen at random among the segments whose end-points are the vertices of a regular 12-gon. What is the probability that the lengths of these three segments are the three side lengths of a triangle with positive area?
Problem 25
Let be defined by
. How many complex numbers
are there such that
and both the real and the imaginary parts of
are integers with absolute value at most
?
$\textbf{(A)} \ 399 \qquad \textbf{(B)} \ 401 \qquad \textbf{(C)} \ 413 \qquad \textbf{(D}} \ 431 \qquad \textbf{(E)} \ 441$ (Error compiling LaTeX. Unknown error_msg)