Difference between revisions of "2014 AMC 10B Problems"
m (Changed the asy diagram to make it resemble the official one more) |
(→Problem 13: added asy diagram) |
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Line 97: | Line 97: | ||
==Problem 13== | ==Problem 13== | ||
− | Six regular hexagons surround a regular hexagon of side length 1 as shown. What is the area of | + | Six regular hexagons surround a regular hexagon of side length <math>1</math> as shown. What is the area of <math>\triangle ABC</math>? |
+ | |||
+ | <asy> | ||
+ | for(int i = 0; i < 6; ++i){ | ||
+ | for(int j = 0; j < 6; ++j){ | ||
+ | draw(sqrt(3)*dir(60*i+30)+dir(60*j)--sqrt(3)*dir(60*i+30)+dir(60*j+60)); | ||
+ | } | ||
+ | } | ||
+ | |||
+ | draw(2*dir(60)--2*dir(180)--2*dir(300)--cycle); | ||
+ | label("A",2*dir(180),dir(180)); | ||
+ | label("B",2*dir(60),dir(60)); | ||
+ | label("C",2*dir(300),dir(300)); | ||
+ | </asy> | ||
==Problem 14== | ==Problem 14== |
Revision as of 20:27, 20 February 2014
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
Leah has coins, all of which are pennies and nickels. If she had one more nickel than she has now, then she would have the same number of pennies and nickels. In cents, how much are Leah's coins worth?
Problem 2
What is ?
Problem 3
Randy drove the first third of his trip on a gravel road, the next miles on pavement, and the remaining one-fifth on a dirt road. In miles how long was Randy's trip?
Problem 4
Susie pays for muffins and
bananas. Calvin spends twice as much paying for
muffins and
bananas. A muffin is how many times as expensive as a banana?
Problem 5
Doug constructs a square window using equal-size panes of glass, as shown. The ratio of the height to width for each pane is
, and the borders around and between the panes are
inches wide. In inches, what is the side length of the square window?
$\textbf{(A)}\ 26\qquad\textbf{(B)}\ 28\qquad\textbf{(C)}\ 30\qquad\textbf{(D)}}\ 32\qquad\textbf{(E)}\ 34$ (Error compiling LaTeX. Unknown error_msg)
Problem 6
Orvin went to the store with just enough money to buy balloons. When he arrived, he discovered that the store had a special sale on balloons: buy
balloon at the regular price and get a second at
off the regular price. What is the greatest number of balloons Orvin could buy?
Problem 7
Suppose and
is
greater than
. What is
?
Problem 8
A truck travels feet every
seconds. There are
feet in a yard. How many yards does the truck travel in
minutes?
Problem 9
For real numbers and
,
What is
?
Problem 10
In the addition shown below and
are distinct digits. How many different values are possible for
?
Problem 11
For the consumer, a single discount of is more advantageous than any of the following discounts:
(1) two successive discounts
(2) three successive
discounts
(3) a
discount followed by a
discount
What is the smallest possible positive integer value of ?
$\textbf{(A)}\ \ 27\qquad\textbf{(B)}\ 28\qquad\textbf{(C)}\ 29\qquad\textbf{(D)}}\ 31\qquad\textbf{(E)}\ 33$ (Error compiling LaTeX. Unknown error_msg)
Problem 12
The largest divisor of is itself. What is its fifth-largest divisor?
Problem 13
Six regular hexagons surround a regular hexagon of side length as shown. What is the area of
?
Problem 14
Danica drove her new car on a trip for a whole number of hours, averaging miles per hour. At the beginning of the trip,
miles was displayed on the odometer, where
is a 3-digit number with
and
. At the end of the trip, the odometer showed
miles. What is
?
Problem 15
Problem 16
Four fair six-sided dice are rolled. What is the probability that at least three of the four dice show the same value?
Problem 17
What is the greatest power of that is a factor of
?
Problem 18
A list of positive integers has a mean of
, a median of
, and a unique mode of
. What is the largest possible value of an integer in the list?
Problem 19
Two concentric circles have radii and
. Two points on the outer circle are chosen independently and uniformly at random. What is the probability that the chord joining the two points intersects the inner circle?
Problem 20
For how many integers is the number
negative?
Problem 21
Trapezoid has parallel sides
of length
and
of length
. The other two sides are of lengths
and
. The angles at
and
are acute. What is the length of the shorter diagonal of
?
Problem 22
Problem 23
Problem 24
The numbers 1, 2, 3, 4, 5 are to be arranged in a circle. An arrangement is bad if it is not true that for every from
to
one can find a subset of the numbers that appear consecutively on the circle that sum to
. Arrangements that differ only by a rotation or a reflection are considered the same. How many different bad arrangements are there?
Problem 25
In a small pond there are eleven lily pads in a row labeled through
. A frog is sitting on pad
. When the frog is on pad
,
, it will jump to pad
with probability
and to pad
with probability
. Each jump is independent of the previous jumps. If the frog reaches pad
it will be eaten by a patiently waiting snake. If the frog reaches pad
it will exit the pond, never to return. what is the probability that the frog will escape being eaten by the snake?