Question 1090518: if gavin turned in five assignments and averaged 83% of gavin received 94%,79%,72%,and 88% on four of the assignments what was his score on the fifth?
Found 2 solutions by Fombitz, greenestamps:
Answer by Fombitz(32388)   (Show Source):
Answer by greenestamps(13215)  (Show Source):
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When working on a problem about averages where the numbers are close together, it can often be faster to find the answer by comparing the individual scores to the average. The idea is that if you want an average of x and one score is x-3, then you need a score of x+3 to balance.
In your example, the known average is 83; and the known scores are 94, 79, 72, and 88.
94-83 = +11
79-83 = -4
72-83 = -11
88-83 = +5
For the four known scores, the "balance" is +1. So the unknown score must have a balance of -1.
So the fifth score is 83-1 = 82.
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