Difference between revisions of "2011 AMC 10B Problems/Problem 2"

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==Problem==
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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?
 
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
 
(A) 80    (B) 82    (C) 85    (D) 90    (E) 95
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==Solution==
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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).

Revision as of 19:28, 25 February 2011

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).

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