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AMC 12 2006 A

Question 1

Sandwiches at Joe's Fast Food cost dollars each and sodas cost dollars each. How many dollars will it cost to purchase sandwiches and sodas?

Solution

  
  2020-07-09 06:38:44

Question 2

Define . What is ?

Solution

  
  2020-07-09 06:38:44

Question 3

The ratio of Mary's age to Alice's age is . Alice is years old. How old is Mary?

Solution

  
  2020-07-09 06:38:44

Question 4

A digital watch displays hours and minutes with AM and PM. What is the largest possible sum of the digits in the display?

Solution

  
  2020-07-09 06:38:44

Question 5

Doug and Dave shared a pizza with equally-sized slices. Doug wanted a plain pizza, but Dave wanted anchovies on half the pizza. The cost of a plain pizza was dollars, and there was an additional cost of dollars for putting anchovies on one half. Dave ate all the slices of anchovy pizza and one plain slice. Doug ate the remainder. Each paid for what he had eaten. How many more dollars did Dave pay than Doug?

Solution

  
  2020-07-09 06:38:44

Question 6

The rectangle is cut into two congruent hexagons, as shown, in such a way that the two hexagons can be repositioned without overlap to form a square. What is ?

Solution

  
  2020-07-09 06:38:44

Question 7

Mary is older than Sally, and Sally is younger than Danielle. The sum of their ages is years. How old will Mary be on her next birthday?

Solution

  
  2020-07-09 06:38:44

Question 8

How many sets of two or more consecutive positive integers have a sum of ?

Solution

  
  2020-07-09 06:38:44

Question 9

Oscar buys pencils and erasers for . A pencil costs more than an eraser, and both items cost a whole number of cents. What is the total cost, in cents, of one pencil and one eraser?

Solution

  
  2020-07-09 06:38:44

Question 10

For how many real values of is an integer?

Solution

  
  2020-07-09 06:38:44

Question 11

Which of the following describes the graph of the equation ?

Solution

  
  2020-07-09 06:38:44

Question 12

A number of linked rings, each 1 cm thick, are hanging on a peg. The top ring has an outside diameter of 20 cm. The outside diameter of each of the outer rings is 1 cm less than that of the ring above it. The bottom ring has an outside diameter of 3 cm. What is the distance, in cm, from the top of the top ring to the bottom of the bottom ring?

Solution

  
  2020-07-09 06:38:44

Question 13

The vertices of a right triangle are the centers of three mutually externally tangent circles, as shown. What is the sum of the areas of the three circles?

Solution

  
  2020-07-09 06:38:44

Question 14

Two farmers agree that pigs are worth dollars and that goats are worth dollars. When one farmer owes the other money, he pays the debt in pigs or goats, with "change" received in the form of goats or pigs as necessary. (For example, a dollar debt could be paid with two pigs, with one goat received in change.) What is the amount of the smallest positive debt that can be resolved in this way?

Solution

  
  2020-07-09 06:38:44

Question 15

Suppose and . What is the smallest possible positive value of ?

Solution

  
  2020-07-09 06:38:44

Question 16

Circles with centers and have radii and , respectively. A common internal tangent intersects the circles at and , respectively. Lines and intersect at , and . What is ?

Solution

  
  2020-07-09 06:38:44

Question 17

Square has side length , a circle centered at has radius , and and are both rational. The circle passes through , and lies on . Point lies on the circle, on the same side of as . Segment is tangent to the circle, and . What is ?

Solution

  
  2020-07-09 06:38:44

Question 18

The function has the property that for each real number in its domain, is also in its domain and

What is the largest set of real numbers that can be in the domain of ?

Solution

  
  2020-07-09 06:38:44

Question 19

Circles with centers and have radii and , respectively. The equation of a common external tangent to the circles can be written in the form with . What is ?

Solution

You need to know this rule for the inner circle of a triangle:
http://www.homesweetlearning.com/resources/math/math910/geometry/inner_cirle_of_triangle.html

Then you draw the line that cuts through the centers of the 2 circles.
You can derive that line's equation
You need to know of the trigonometry "double angle formula"
https://www.homesweetlearning.com/resources/math/math910/trigonometry/functions_on_x-y_plane.html

Then you can derive the equation for the tangent line, then you can figure out value of b.
  
allenx123456  2016-12-20 19:39:09

Question 20

A bug starts at one vertex of a cube and moves along the edges of the cube according to the following rule. At each vertex the bug will choose to travel along one of the three edges emanating from that vertex. Each edge has equal probability of being chosen, and all choices are independent. What is the probability that after seven moves the bug will have visited every vertex exactly once?

Solution

First, figure out the total possible paths. The bug is asked to move 7 moves, with each move 3 possible choices. Therefore, the total possible paths = 3 to the power of 7 = 2187.

Now, figure out of all the possible paths, how many cover all 8 vertexes exactly once.

Draw the cube, and letter-mark each vertex. There are 2 scenarios:
1. Finish top face, then go down to bottom face
2. Finish only 3 vertexes on top face, then go down to bottom face.

In #1, there are 3*2*2=12 good paths
In #2, there are 3*2*1=6 good paths

Therefore, the possibility is (12+6)/2187.
  
jimmy  2016-09-16 15:07:18

Question 21

Let

and

.

What is the ratio of the area of to the area of ?

Solution

  
  2020-07-09 06:38:44

Question 22

A circle of radius is concentric with and outside a regular hexagon of side length . The probability that three entire sides of hexagon are visible from a randomly chosen point on the circle is . What is ?

Solution

  
  2020-07-09 06:38:44

Question 23

Given a finite sequence of real numbers, let be the sequence

of real numbers. Define and, for each integer , , define . Suppose , and let . If , then what is ?

Solution

  
  2020-07-09 06:38:44

Question 24

The expression

is simplified by expanding it and combining like terms. How many terms are in the simplified expression?

Solution

  
  2020-07-09 06:38:44

Question 25

How many non-empty subsets of have the following two properties?

No two consecutive integers belong to .

If contains elements, then contains no number less than .

Solution

  
  2020-07-09 06:38:44

Answer Keys


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