SOLUTION: Tom has taken 5 of the 8 equally weighted tests in his U.S. History class this semester, and he has an average score of exactly 78.0 points. How many points does he need to earn on

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Question 411254: Tom has taken 5 of the 8 equally weighted tests in his U.S. History class this semester, and he has an average score of exactly 78.0 points. How many points does he need to earn on the 6th test to bring his average score up to exactly 80.0 points?
The answer is 90. Can someone explain how to get this answer?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

 Averaged 78 pts on first 5 tests for a total of 390 Pts on these tests.

Let x represent score on his 6th test.

Question states***

  (390+x)/6 = 80

Solving for x

    x = 480 -390

    x = 90



CHECKING our Answer***

 480/6 = 80