Riya's score

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Riya's score

by ritula » Sun Sep 14, 2008 11:18 pm
What was Riya's score on the fourth physics test she took?

(A) Her score on the fourth test was 12 points higher than her average (arithmetic mean) score on the first three tests she took.

(B) Her score on the fourth test raised her average (arithmetic mean) test score from 87 to 90.

Ans: B
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by alescau » Mon Sep 15, 2008 12:01 am
(1) doesn't give us anything to work with.
(2) (87*3 + x)/4 = 90. We can solve this, thus we can answer the question using this.

87*3 is the same as the sum of the scores from the first three tests, b/c (Sum first three)/3=(Avg first three)