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Susan received grades of 78, 93, 82, and 76 on four math exams. What is the lowest score she can receive on her next math exam and have an average of at least 85 on the five exams?

A) 96
B) 94
C) 92
D) 90
E) 88

Respuesta :

Answers:
Choice A) 96

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Explanation:

The original list of scores is {78, 93, 82, 76}
Add x to the list to get this new list {78, 93, 82, 76, x}

Let's find the average of the new set
Add up the values and divide by 5. We force this average to be 85 since this is the grade Susan wants
(78+93+82+76+x)/5 = 85
(329+x)/5 = 85
329+x = 85*5
329+x = 425
x = 425-329
x = 96

So if Susan gets a 96 or greater on the fifth test, then she'll have an average of at least 85 (that score or greater)

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