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AMC 12 2013 A

Question 1

Square has side length . Point is on , and the area of is . What is ?

Solution

  
  2020-07-09 06:38:26

Question 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?

Solution

  
  2020-07-09 06:38:26

Question 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?

Solution

  
  2020-07-09 06:38:26

Question 4

What is the value of

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 8

Given that and are distinct nonzero real numbers such that , what is ?

Solution

  
  2020-07-09 06:38:26

Question 9

In , and . Points and are on sides , , and , respectively, such that and are parallel to and , respectively. What is the perimeter of parallelogram ?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 14

The sequence

, , , ,

is an arithmetic progression. What is ?

Solution

  
  2020-07-09 06:38:26

Question 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?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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 does the pirate receive?

Solution

  
  2020-07-09 06:38:26

Question 18

Six spheres of radius are positioned so that their centers are at the vertices of a regular hexagon of side length . The six 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?

Solution

  
  2020-07-09 06:38:26

Question 19

In , , and . A circle with center and radius intersects at points and . Moreover and have integer lengths. What is ?

Solution

  
  2020-07-09 06:38:26

Question 20

Let be the set . For , define to mean that either or . How many ordered triples of elements of have the property that , , and ?

Solution 1

See my solution in attached link.  mysolution.txt
  
jimmy  2016-09-27 18:01:49

Solution 2

First, derive the relationship of x, y, z. Find out the scenarios and then do a table to count all the possible combinations.
  
jimmy  2016-09-27 17:46:36

Question 21

Consider . Which of the following intervals contains ?

Solution

  
  2020-07-09 06:38:26

Question 22

A palindrome is a nonnegative 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?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Question 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?

Solution

  
  2020-07-09 06:38:26

Question 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 ?

Solution

  
  2020-07-09 06:38:26

Answer Keys


Question 1: E
Question 2: C
Question 3: E
Question 4: C
Question 5: B
Question 6: B
Question 7: C
Question 8: D
Question 9: C
Question 10: D
Question 11: C
Question 12: A
Question 13: B
Question 14: B
Question 15: D
Question 16: E
Question 17: D
Question 18: B
Question 19: D
Question 20: B
Question 21: A
Question 22: E
Question 23: C
Question 24: E
Question 25: A