Difference between revisions of "2008 AMC 10A Problems"
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+ | {{AMC10 Problems|year=2008|ab=A}} | ||
==Problem 1== | ==Problem 1== | ||
A bakery owner turns on his doughnut machine at <math>\text{8:30}\ {\small\text{AM}}</math>. At <math>\text{11:10}\ {\small\text{AM}}</math> the machine has completed one third of the day's job. At what time will the doughnut machine complete the job? | A bakery owner turns on his doughnut machine at <math>\text{8:30}\ {\small\text{AM}}</math>. At <math>\text{11:10}\ {\small\text{AM}}</math> the machine has completed one third of the day's job. At what time will the doughnut machine complete the job? | ||
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==Problem 2== | ==Problem 2== | ||
− | A square is drawn inside a rectangle. The ratio of the width of the rectangle to a side of the square is <math>2:1</math>. The ratio of the rectangle's length to its width is <math>2:1</math>. What percent of the rectangle's area is | + | A square is drawn inside a rectangle. The ratio of the width of the rectangle to a side of the square is <math>2:1</math>. The ratio of the rectangle's length to its width is <math>2:1</math>. What percent of the rectangle's area is in the square? |
<math>\mathrm{(A)}\ 12.5\qquad\mathrm{(B)}\ 25\qquad\mathrm{(C)}\ 50\qquad\mathrm{(D)}\ 75\qquad\mathrm{(E)}\ 87.5</math> | <math>\mathrm{(A)}\ 12.5\qquad\mathrm{(B)}\ 25\qquad\mathrm{(C)}\ 50\qquad\mathrm{(D)}\ 75\qquad\mathrm{(E)}\ 87.5</math> | ||
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is an integer. Which of the following statements must be true about <math>x</math>? | is an integer. Which of the following statements must be true about <math>x</math>? | ||
− | <math>\mathrm{(A)}\ \text{It is negative.}\qquad\mathrm{(B)}\ \text{It is even, but not necessarily a multiple of 3.}\\\qquad\mathrm{(C)}\ \text{It is a multiple of 3, but not necessarily even.}\\\qquad\mathrm{(D)}\ \text{It is a multiple of 6, but not necessarily a multiple of 12.}\\\qquad\mathrm{(E)}\ \text{It is a multiple of 12.}</math> | + | <math>\mathrm{(A)}\ \text{It is negative.}\\\qquad\mathrm{(B)}\ \text{It is even, but not necessarily a multiple of 3.}\\\qquad\mathrm{(C)}\ \text{It is a multiple of 3, but not necessarily even.}\\\qquad\mathrm{(D)}\ \text{It is a multiple of 6, but not necessarily a multiple of 12.}\\\qquad\mathrm{(E)}\ \text{It is a multiple of 12.}</math> |
[[2008 AMC 10A Problems/Problem 9|Solution]] | [[2008 AMC 10A Problems/Problem 9|Solution]] | ||
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==Problem 12== | ==Problem 12== | ||
In a collection of red, blue, and green marbles, there are <math>25\%</math> more red marbles than blue marbles, and there are <math>60\%</math> more green marbles than red marbles. Suppose that there are <math>r</math> red marbles. What is the total number of marbles in the collection? | In a collection of red, blue, and green marbles, there are <math>25\%</math> more red marbles than blue marbles, and there are <math>60\%</math> more green marbles than red marbles. Suppose that there are <math>r</math> red marbles. What is the total number of marbles in the collection? | ||
− | |||
<math>\mathrm{(A)}\ 2.85r\qquad\mathrm{(B)}\ 3r\qquad\mathrm{(C)}\ 3.4r\qquad\mathrm{(D)}\ 3.85r\qquad\mathrm{(E)}\ 4.25r</math> | <math>\mathrm{(A)}\ 2.85r\qquad\mathrm{(B)}\ 3r\qquad\mathrm{(C)}\ 3.4r\qquad\mathrm{(D)}\ 3.85r\qquad\mathrm{(E)}\ 4.25r</math> | ||
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==Problem 16== | ==Problem 16== | ||
− | Points <math>A</math> and <math>B</math> lie on a | + | Points <math>A</math> and <math>B</math> lie on a circle centered at <math>O</math>, and <math>\angle AOB = 60^\circ</math>. A second circle is internally tangent to the first and tangent to both <math>\overline{OA}</math> and <math>\overline{OB}</math>. What is the ratio of the area of the smaller circle to that of the larger circle? |
<math>\mathrm{(A)}\ \frac{1}{16}\qquad\mathrm{(B)}\ \frac{1}{9}\qquad\mathrm{(C)}\ \frac{1}{8}\qquad\mathrm{(D)}\ \frac{1}{6}\qquad\mathrm{(E)}\ \frac{1}{4}</math> | <math>\mathrm{(A)}\ \frac{1}{16}\qquad\mathrm{(B)}\ \frac{1}{9}\qquad\mathrm{(C)}\ \frac{1}{8}\qquad\mathrm{(D)}\ \frac{1}{6}\qquad\mathrm{(E)}\ \frac{1}{4}</math> | ||
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==Problem 17== | ==Problem 17== | ||
− | An equilateral triangle has side length 6. What is the area of the region containing all points that are outside the triangle but not more than 3 units from a point | + | An equilateral triangle has side length 6. What is the area of the region containing all points that are outside the triangle but not more than 3 units from a point on the triangle? |
<math>\mathrm{(A)}\ 36+24\sqrt{3}\qquad\mathrm{(B)}\ 54+9\pi\qquad\mathrm{(C)}\ 54+18\sqrt{3}+6\pi\qquad\mathrm{(D)}\ \left(2\sqrt{3}+3\right)^2\pi\\\mathrm{(E)}\ 9\left(\sqrt{3}+1\right)^2\pi</math> | <math>\mathrm{(A)}\ 36+24\sqrt{3}\qquad\mathrm{(B)}\ 54+9\pi\qquad\mathrm{(C)}\ 54+18\sqrt{3}+6\pi\qquad\mathrm{(D)}\ \left(2\sqrt{3}+3\right)^2\pi\\\mathrm{(E)}\ 9\left(\sqrt{3}+1\right)^2\pi</math> | ||
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<asy> | <asy> | ||
+ | size(4cm); | ||
import three; | import three; | ||
unitsize(3cm); | unitsize(3cm); | ||
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==Problem 25== | ==Problem 25== | ||
− | A round table has radius <math>4</math>. Six rectangular place mats are placed on the table. Each place mat has width <math>1</math> and length <math>x</math> as shown. They are positioned so that each mat has two corners on the edge of the table, these two corners being end points of the same side of length <math>x</math>. | + | A round table has radius <math>4</math>. Six rectangular place mats are placed on the table. Each place mat has width <math>1</math> and length <math>x</math> as shown. They are positioned so that each mat has two corners on the edge of the table, these two corners being end points of the same side of length <math>x</math>. Furthermore, the mats are positioned so that the inner corners each touch an inner corner of an adjacent mat. What is <math>x</math>? |
<asy>unitsize(4mm); | <asy>unitsize(4mm); | ||
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[[2008 AMC 10A Problems/Problem 25|Solution]] | [[2008 AMC 10A Problems/Problem 25|Solution]] | ||
+ | |||
==See also== | ==See also== | ||
{{AMC10 box|year=2008|ab=A|before=[[2007 AMC 10B Problems]]|after=[[2008 AMC 10B Problems]]}} | {{AMC10 box|year=2008|ab=A|before=[[2007 AMC 10B Problems]]|after=[[2008 AMC 10B Problems]]}} |
Latest revision as of 15:08, 18 February 2023
2008 AMC 10A (Answer Key) Printable versions: • AoPS Resources • PDF | ||
Instructions
| ||
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
- 26 See also
Problem 1
A bakery owner turns on his doughnut machine at . At
the machine has completed one third of the day's job. At what time will the doughnut machine complete the job?
Problem 2
A square is drawn inside a rectangle. The ratio of the width of the rectangle to a side of the square is . The ratio of the rectangle's length to its width is
. What percent of the rectangle's area is in the square?
Problem 3
For the positive integer , let
denote the sum of all the positive divisors of
with the exception of
itself. For example,
and
. What is
?
Problem 4
Suppose that of
bananas are worth as much as
oranges. How many oranges are worth as much as
of
bananas?
Problem 5
Which of the following is equal to the product
Problem 6
A triathlete competes in a triathlon in which the swimming, biking, and running segments are all of the same length. The triathlete swims at a rate of 3 kilometers per hour, bikes at a rate of 20 kilometers per hour, and runs at a rate of 10 kilometers per hour. Which of the following is closest to the triathlete's average speed, in kilometers per hour, for the entire race?
Problem 7
The fraction
simplifies to which of the following?
Problem 8
Heather compares the price of a new computer at two different stores. Store offers
off the sticker price followed by a
rebate, and store
offers
off the same sticker price with no rebate. Heather saves
by buying the computer at store
instead of store
. What is the sticker price of the computer, in dollars?
Problem 9
Suppose that
is an integer. Which of the following statements must be true about
?
Problem 10
Each of the sides of a square with area
is bisected, and a smaller square
is constructed using the bisection points as vertices. The same process is carried out on
to construct an even smaller square
. What is the area of
?
Problem 11
While Steve and LeRoy are fishing 1 mile from shore, their boat springs a leak, and water comes in at a constant rate of 10 gallons per minute. The boat will sink if it takes in more than 30 gallons of water. Steve starts rowing toward the shore at a constant rate of 4 miles per hour while LeRoy bails water out of the boat. What is the slowest rate, in gallons per minute, at which LeRoy can bail if they are to reach the shore without sinking?
Problem 12
In a collection of red, blue, and green marbles, there are more red marbles than blue marbles, and there are
more green marbles than red marbles. Suppose that there are
red marbles. What is the total number of marbles in the collection?
Problem 13
Doug can paint a room in hours. Dave can paint the same room in
hours. Doug and Dave paint the room together and take a one-hour break for lunch. Let
be the total time, in hours, required for them to complete the job working together, including lunch. Which of the following equations is satisfied by
?
Problem 14
Older television screens have an aspect ratio of . That is, the ratio of the width to the height is
. The aspect ratio of many movies is not
, so they are sometimes shown on a television screen by "letterboxing" - darkening strips of equal height at the top and bottom of the screen, as shown. Suppose a movie has an aspect ratio of
and is shown on an older television screen with a
-inch diagonal. What is the height, in inches, of each darkened strip?
Problem 15
Yesterday Han drove 1 hour longer than Ian at an average speed 5 miles per hour faster than Ian. Jan drove 2 hours longer than Ian at an average speed 10 miles per hour faster than Ian. Han drove 70 miles more than Ian. How many more miles did Jan drive than Ian?
Problem 16
Points and
lie on a circle centered at
, and
. A second circle is internally tangent to the first and tangent to both
and
. What is the ratio of the area of the smaller circle to that of the larger circle?
Problem 17
An equilateral triangle has side length 6. What is the area of the region containing all points that are outside the triangle but not more than 3 units from a point on the triangle?
Problem 18
A right triangle has perimeter 32 and area 20. What is the length of its hypotenuse?
Problem 19
Rectangle lies in a plane with
and
. The rectangle is rotated
clockwise about
, then rotated
clockwise about the point
moved to after the first rotation. What is the length of the path traveled by point
?
Problem 20
Trapezoid has bases
and
and diagonals intersecting at
. Suppose that
,
, and the area of
is
. What is the area of trapezoid
?
Problem 21
A cube with side length is sliced by a plane that passes through two diagonally opposite vertices
and
and the midpoints
and
of two opposite edges not containing
or
, as shown. What is the area of quadrilateral
?
Problem 22
Jacob uses the following procedure to write down a sequence of numbers. First he chooses the first term to be 6. To generate each succeeding term, he flips a fair coin. If it comes up heads, he doubles the previous term and subtracts 1. If it comes up tails, he takes half of the previous term and subtracts 1. What is the probability that the fourth term in Jacob's sequence is an integer?
Problem 23
Two subsets of the set are to be chosen so that their union is
and their intersection contains exactly two elements. In how many ways can this be done, assuming that the order in which the subsets are chosen does not matter?
Problem 24
Let . What is the units digit of
?
Problem 25
A round table has radius . Six rectangular place mats are placed on the table. Each place mat has width
and length
as shown. They are positioned so that each mat has two corners on the edge of the table, these two corners being end points of the same side of length
. Furthermore, the mats are positioned so that the inner corners each touch an inner corner of an adjacent mat. What is
?
See also
2008 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by 2007 AMC 10B Problems |
Followed by 2008 AMC 10B Problems | |
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 | ||
All AMC 10 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.