A student's scores on 4 tests are 65, 70, 60, 90. What score is needed on the next test for an average of 70 over all 5 tests?
Answer and explanation
Correct answer: C. 65
- Step 1: The total needed is 70 x 5 = 350.
- Step 2: The scores so far add up to 285, so the next test needs 350 - 285 = 65.
Answer
65.
Why not the others: Scoring 70 only matches the target if the earlier average is already 70; -5 uses only 4 tests in the total.
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