A student's scores on 3 tests are 80, 70, 70. What score is needed on the next test for an average of 70 over all 4 tests?
Answer and explanation
Correct answer: D. 60
- Step 1: The total needed is 70 x 4 = 280.
- Step 2: The scores so far add up to 220, so the next test needs 280 - 220 = 60.
Answer
60.
Why not the others: Scoring 70 only matches the target if the earlier average is already 70; -10 uses only 3 tests in the total.
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