Section: Math Section 1

4) Lenny's average score after 3 tests is 88. What score on the 4th test would bring Lenny's average up to exactly 90?

1. 92
2. 93
3. 94
4. 95
5. 96

The best way to deal with changing averages is to use the
sum. Use the old average to figure out the total of the first
3 scores:

Sum of first 4 scores = (3)(88) = 264

Use the new average to figure out the total he needs after the 4th score:

Sum of 4 scores (4)(90) = 360

To get his sum from 264 to 360, Lenny needs to score 360 - 264 = 96.