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A student’s average (arithmetic mean) test score on 4 tests
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11 Apr 2020, 11:24
11 Apr 2020, 11:24
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A student’s average (arithmetic mean) test score on 4 tests is 80. What must be the student’s score on a 5th test for the student’s average score on the 5 tests to be 82?
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Re: A student’s average (arithmetic mean) test score on 4 tests
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11 Apr 2020, 11:25
11 Apr 2020, 11:25
A student’s average (arithmetic mean) test score on 4 tests is 80.
This tells us that: (sum of all 4 scores)/4 = 80
Multiply both sides of the equation by 4 to get: sum of all 4 scores = 320
What must be the student’s score on a 5th test for the student’s average score on the 5 tests to be 82?
This tells us that: (sum of all 5 scores)/5 = 82
Multiply both sides of the equation by 5 to get: sum of all 5 scores = 410
Notice that the sum of all 5 scores is 90 GREATER THAN the sum of all 4 scores
The extra (5th) score must account for this difference
So the fifth score must be 90
This tells us that: (sum of all 4 scores)/4 = 80
Multiply both sides of the equation by 4 to get: sum of all 4 scores = 320
What must be the student’s score on a 5th test for the student’s average score on the 5 tests to be 82?
This tells us that: (sum of all 5 scores)/5 = 82
Multiply both sides of the equation by 5 to get: sum of all 5 scores = 410
Notice that the sum of all 5 scores is 90 GREATER THAN the sum of all 4 scores
The extra (5th) score must account for this difference
So the fifth score must be 90
gmatclubot
Re: A student’s average (arithmetic mean) test score on 4 tests [#permalink]
11 Apr 2020, 11:25
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