# Difference between revisions of "2009 AMC 8 Problems/Problem 21"

Mrdavid445 (talk | contribs) (Created page with "==Problem== Andy and Bethany have a rectangular array of numbers with <math> 40</math> rows and <math> 75</math> columns. Andy adds the numbers in each row. The average of his <...") |
(→Problem) |
||

Line 8: | Line 8: | ||

\textbf{(D)}\ \frac{15}{8} \qquad | \textbf{(D)}\ \frac{15}{8} \qquad | ||

\textbf{(E)}\ \frac{225}{64}</math> | \textbf{(E)}\ \frac{225}{64}</math> | ||

+ | |||

+ | ==Solution== | ||

+ | |||

+ | First, note that <math>40A=75B=\text{sum of the numbers in the array}</math>. Solving for <math> \frac{A}{B}</math>, we get <math> \frac{75}{40} =\frac{15}{8} =\frac{A}{B}</math>. <math> \boxed{\text{D}}</math>. |

## Revision as of 09:31, 27 April 2012

## Problem

Andy and Bethany have a rectangular array of numbers with rows and columns. Andy adds the numbers in each row. The average of his sums is . Bethany adds the numbers in each column. The average of her sums is . What is the value of ?

## Solution

First, note that . Solving for , we get . .