SOLUTION: if a kid takes 4 tests and it is his average grade and he wants to score a 90 and his first 3 test grades were 84, 93, and 88 what would the last test score be to get an average of

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Question 148543: if a kid takes 4 tests and it is his average grade and he wants to score a 90 and his first 3 test grades were 84, 93, and 88 what would the last test score be to get an average of 90?
Answer by mangopeeler07(462) About Me  (Show Source):
You can put this solution on YOUR website!
Set up an equation for the average: %2884%2B93%2B88%2Bx%29%2F4=90

Combine like terms:

%28265%2Bx%29%2F4=90

Multiply both sides by 4.

265%2Bx=360

Subtract 265 from both sides

x=95

So for the average grade to be 90, the person would have to get a 95.