Difference between revisions of "2015 AMC 10B Problems/Problem 15"
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===Solution 1=== | ===Solution 1=== | ||
Let the amount of people be <math>p</math>, horses be <math>h</math>, sheep be <math>s</math>, cows be <math>c</math>, and ducks be <math>d</math>. | Let the amount of people be <math>p</math>, horses be <math>h</math>, sheep be <math>s</math>, cows be <math>c</math>, and ducks be <math>d</math>. | ||
− | We know <cmath> | + | We know <cmath>3h=p</cmath> <cmath>4c=s</cmath> <cmath>3p=d</cmath> Then the total amount of people, horses, sheep, cows, and ducks may be written as <math>p+h+s+c+d = 3h+h+4c+c+(3\times3h)</math>. This is equivalent to <math>13h+5c</math>. Looking through the options, we see <math>47</math> is impossible to make for integer values of <math>h</math> and <math>c</math>. So the answer is <math>\boxed{\textbf{(B)} 47}</math>. |
===Solution 2=== | ===Solution 2=== |
Revision as of 11:51, 13 July 2020
Problem
The town of Hamlet has people for each horse,
sheep for each cow, and
ducks for each person. Which of the following could not possibly be the total number of people, horses, sheep, cows, and ducks in Hamlet?
Solution
Solution 1
Let the amount of people be , horses be
, sheep be
, cows be
, and ducks be
.
We know
Then the total amount of people, horses, sheep, cows, and ducks may be written as
. This is equivalent to
. Looking through the options, we see
is impossible to make for integer values of
and
. So the answer is
.
Solution 2
As the solution above says, the total amount of people, horses, sheep, cows, and ducks may be written as . However, instead of going through each of the solutions and testing the the options, you can use the Chicken McNugget Theorem to find the greatest number of people, horses, sheep, cows, and ducks that cannot be written in the form
.
so our answer is
.
See Also
2015 AMC 10B (Problems • Answer Key • Resources) | ||
Preceded by Problem 14 |
Followed by Problem 16 | |
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.