SOLUTION: three test scores - 79,88,93 If the fourth test counts twice as much as the other three tests, then what score must you get on fourth test to have a test average of 90?

Question 340242: three test scores - 79,88,93
If the fourth test counts twice as much as the other three tests, then what score must you get on fourth test to have a test average of 90?
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
Set this up like this:
(79 + 88 + 93 + X + X) / 5 = 90 (notice x is in there twice)
Now multiply by five...
(79 + 88 + 93 + X + X) = 450
combine like terms...
260 + 2X = 450
subtract 260...
2X = 190
and
X >= 95
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