SOLUTION: The mean of three test grades is 74. What must the fourth test grade be to increase the mean to 78?

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Question 780578: The mean of three test grades is 74. What must the fourth test grade be to increase the mean to 78?
Answer by rfer(16322) About Me  (Show Source):
You can put this solution on YOUR website!
(74+74+74+x)/4=78
222+x=78*4
222+x=312
x=312-222
x=90