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AMC 10 2003 A

Question 1

What is the difference between the sum of the first even counting numbers and the sum of the first odd counting numbers?

Solution

  
  2020-07-09 06:36:01

Question 2

Members of the Rockham Soccer League buy socks and T-shirts. Socks cost $4 per pair and each T-shirt costs $5 more than a pair of socks. Each member needs one pair of socks and a shirt for home games and another pair of socks and a shirt for away games. If the total cost is $2366, how many members are in the League?

Solution

2*(4*M + 9*M) = 2366
M=91
  
  2017-01-21 17:01:00

Question 3

A solid box is cm by cm by cm. A new solid is formed by removing a cube cm on a side from each corner of this box. What percent of the original volume is removed?

Solution

  
  2020-07-09 06:36:01

Question 4

It takes Mary minutes to walk uphill km from her home to school, but it takes her only minutes to walk from school to her home along the same route. What is her average speed, in km/hr, for the round trip?

Solution

  
  2020-07-09 06:36:01

Question 5

Let and denote the solutions of . What is the value of ?

Solution

  
  2020-07-09 06:36:01

Question 6

Define to be for all real numbers and . Which of the following statements is not true?

for all and

for all and

for all

for all

if

Solution

  
  2020-07-09 06:36:01

Question 7

How many non-congruent triangles with perimeter have integer side lengths?

Solution

  
  2020-07-09 06:36:01

Question 8

What is the probability that a randomly drawn positive factor of is less than ?

Solution

  
  2020-07-09 06:36:01

Question 9

Simplify

.

Solution

  
  2020-07-09 06:36:01

Question 10

The polygon enclosed by the solid lines in the figure consists of 4 congruent squares joined edge-to-edge. One more congruent square is attached to an edge at one of the nine positions indicated. How many of the nine resulting polygons can be folded to form a cube with one face missing?


Solution

  
  2020-07-09 06:36:01

Question 11

The sum of the two 5-digit numbers and is . What is ?

Solution

AMC
AMC
-----
1234

Since 2+2=4, 7+7=4, C must be either 2 or 7
If C=2, we must make M+M=3 or 13. No digits can do that. So C=7.

Now moving on to 10th digit:
1+1 +1=3, 6+6 +1=13, so M must be 1 or 6.

If M is 6, then we must make A+A=11. No digits can do that. So M=1.

If M is 1, then we will have A=6;

So A+M+C = 6+1+7 = 14
  
  2017-01-21 17:08:28

Question 12

A point is randomly picked from inside the rectangle with vertices , , , and . What is the probability that ?

Solution

Any points within the yellow area below will meet the requirement of x
  
  2017-01-21 17:18:39

Question 13

The sum of three numbers is . The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

Solution

Let the numbers be x, y, and z in that order. The given tells us that

y=7z
x=4(y+z)=4(7z+z)=4(8z)=32z

x+y+z=32z+7z+z=40z=20

So z=1/2
y=7z=7/2
x=4(y+z)=4(1/2 + 7/2)=32/2=16

So xyz=16 * 7/2 * 1/2 = 28
  
  2017-01-21 22:08:17

Question 14

Let be the largest integer that is the product of exactly 3 distinct prime numbers , , and , where and are single digits. What is the sum of the digits of ?

Solution

  
  2020-07-09 06:36:01

Question 15

What is the probability that an integer in the set is divisible by and not divisible by ?

Solution

There are 100 integers in the set.

Since every 2 integer is divisible by 2, there are 100/2=50 integers divisible by 2 in the set.

To be divisible by both 2 and 3, a number must be divisible by 2*3=6.

Since every 6 integer is divisible by 6, there are 100/6=16 integers divisible by both 2 and 3 in the set.

So there are 50-16=34 integers in this set that are divisible by 2 and not divisible by 3.

Therefore, the desired probability is 34/100 = 17/50
  
  2017-02-08 04:35:45

Question 16

What is the units digit of ?

Solution

  
  2020-07-09 06:36:01

Question 17

The number of inches in the perimeter of an equilateral triangle equals the number of square inches in the area of its circumscribed circle. What is the radius, in inches, of the circle?

Solution

  
  2020-07-09 06:36:01

Question 18

What is the sum of the reciprocals of the roots of the equation

?

Solution

Multiplying both sides by x:

2003/2004 * x^2+1*x+1=0

x^2 + 2004/2003 * x + 2004/2003 =0

Let the roots be a and b.

The problem is asking for 1/a+1/b = (a+b)/ab

By Vieta's formulas:

a+b= - 2004/2003

ab=2004/2003

So the answer is (a+b)/ab=-1
  
  2017-02-08 04:41:11

Question 19

A semicircle of diameter sits at the top of a semicircle of diameter , as shown. The shaded area inside the smaller semicircle and outside the larger semicircle is called a lune. Determine the area of this lune.

Solution

Note that in the diagram below, the triangle is a regular triangle and its sides are 1. the radius of the semicircle is 1/2. Area B is the difference between the 60 degree sector and the regular triangle. The shaded area A is the difference between the area of the semi-circle and the area B.

  
  2017-02-08 04:47:36

Question 20

A base-10 three digit number is selected at random. Which of the following is closest to the probability that the base-9 representation and the base-11 representation of are both three-digit numerals?

Solution

  
  2020-07-09 06:36:01

Question 21

Pat is to select six cookies from a tray containing only chocolate chip, oatmeal, and peanut butter cookies. There are at least six of each of these three kinds of cookies on the tray. How many different assortments of six cookies can be selected?

Solution

  
  2020-07-09 06:36:01

Question 22

In rectangle , we have , , is on with , is on with , line intersects line at , and is on line with . Find the length of .

Solution

  
  2020-07-09 06:36:01

Question 23

A large equilateral triangle is constructed by using toothpicks to create rows of small equilateral triangles. For example, in the figure we have rows of small congruent equilateral triangles, with small triangles in the base row. How many toothpicks would be needed to construct a large equilateral triangle if the base row of the triangle consists of small equilateral triangles?

Solution

  
  2020-07-09 06:36:01

Question 24

Sally has five red cards numbered through and four blue cards numbered through . She stacks the cards so that the colors alternate and so that the number on each red card divides evenly into the number on each neighboring blue card. What is the sum of the numbers on the middle three cards?

Solution

  
  2020-07-09 06:36:01

Question 25

Let be a -digit number, and let and be the quotient and the remainder, respectively, when is divided by . For how many values of is divisible by ?

Solution

  
  2020-07-09 06:36:01

Answer Keys


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