2012 AMC 10A Problems/Problem 14: Difference between revisions
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== Problem == | |||
Chubby makes nonstandard checkerboards that have <math>31</math> squares on each side. The checkerboards have a black square in every corner and alternate red and black squares along every row and column. How many black squares are there on such a checkerboard? | Chubby makes nonstandard checkerboards that have <math>31</math> squares on each side. The checkerboards have a black square in every corner and alternate red and black squares along every row and column. How many black squares are there on such a checkerboard? | ||
<math> \textbf{(A)}\ 480 | <math> \textbf{(A)}\ 480 \qquad\textbf{(B)}\ 481 \qquad\textbf{(C)}\ 482 \qquad\textbf{(D)}\ 483 \qquad\textbf{(E)}\ 484</math> | ||
\qquad\textbf{(B)}\ 481 | |||
\qquad\textbf{(C)}\ 482 | == Solution == | ||
\qquad\textbf{(D)}\ 483 | |||
\qquad\textbf{(E)}\ 484 | There are 15 rows with 15 black tiles, and 16 rows with 16 black tiles, so the answer is <math>15^2+16^2 =225+256= \boxed{\textbf{(B)}\ 481}</math> | ||
== See Also == | |||
{{AMC10 box|year=2012|ab=A|num-b=13|num-a=15}} | |||
Revision as of 23:37, 8 February 2012
Problem
Chubby makes nonstandard checkerboards that have 
squares on each side. The checkerboards have a black square in every corner and alternate red and black squares along every row and column. How many black squares are there on such a checkerboard?
Solution
There are 15 rows with 15 black tiles, and 16 rows with 16 black tiles, so the answer is 
See Also
| 2012 AMC 10A (Problems • Answer Key • Resources) | ||
| Preceded by Problem 13 |
Followed by Problem 15 | |
| 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 | ||
