2011 AMC 10B Problems/Problem 2

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Problem

Josanna's test scores to date are 90, 80, 70, 60, and 85. Her goal is to raise her test average at least 3 points with her next test. What is the minimum test score she would need to accomplish this goal?

(A) 80 (B) 82 (C) 85 (D) 90 (E) 95


Solution

The average of her current scores is 77. To raise it 3 points, she needs an average of 80, and so after her 6 tests, a sum of 480. Her current sum is 385, so she needs a 480 - 385 = 95 (E).