SOLUTION: To earn an A in a course, a student must get an average score of 90 on five tests. If her first four scores are 92, 86, 79, and 96, what score does she need on the last test to o

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Question 1168156: To earn an A in a course, a student must get an average score of 90 on five
tests. If her first four scores are 92, 86, 79, and 96, what score does she need
on the last test to obtain a 90 average?
Found 2 solutions by math_helper, greenestamps:
Answer by math_helper(2461)   (Show Source): You can put this solution on YOUR website!

Solve for x.
You should get x = 97
Answer by greenestamps(13200)   (Show Source): You can put this solution on YOUR website!


An average of 90 on 5 tests means a total of 450 points:



Solve for x using basic algebra.

In cases like this involving the average of a set of numbers that are all close together, there is another quick way to solve the problem -- by balancing the "overs" and "unders".

Comparing each score to the desired average....
   92:  +2
   86:  -4
   79: -11
   96:  +6
   -------
 total: -7


Through the first four tests, the student is 7 points under the total they need, so the 5th test must be 7 points over the desired average.

ANSWER: 90+7 = 97
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