A student's scores on 5 tests are 75, 90, 75, 80, 90. What score is needed on the next test for an average of 75 over all 6 tests?
Answer and explanation
Correct answer: D. 40
- Step 1: The total needed is 75 x 6 = 450.
- Step 2: The scores so far add up to 410, so the next test needs 450 - 410 = 40.
Answer
40.
Why not the others: Scoring 75 only matches the target if the earlier average is already 75; -35 uses only 5 tests in the total.
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