GMAT Quantitative Reasoning Practice Test 1

This is an average problem, so use the average formula. If the average of 7 numbers is 12.2 , we can solve for their sum: 7×12.2=85.4 . If four of these numbers total 42.8, then by subtracting 42.8 from 85.4, we get the sum of the other three numbers, 42.6. To find the average of these three numbers, we divide their sum by their number:

42.6

3

=14.2.