Question 819260
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If his average on the first 5 tests is 88, then the total of the first 5 scores must be 5 times 88.

If he wants an overall average of 90 on 6 tests then the total of his points must be 6 times 90.

So he must need to score (6 * 90) - (5 * 88) on the sixth test.

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