E. 88

The student must score at least an 80 for sure. If he scores an 8, then he will need to score 2 pots for each of the 4 other tests to "make up" the difference. They each were at 78 (at least the average is, but this is a small point and doesn't matter to the answer). So 4 tests that were each 2 points short of the 80 average that is desired means the next test must be 8 points higher than the desired average, so 80+8 = 88.

petercao wrote:

A student’s average (arithmetic mean) test score on 4 tests is 78. What must be the student’s score on a 5th test for the student’s average score on the 5 tests to be 80?

A. 80

B. 82

C. 84

D. 86

E. 88

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J Allen Morris

**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

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