SOLUTION: Going into the final exam, which will count as two tests, Brooke has test scores 80, 83, 71, 61 and 95. What score does Brooke need on the final in order to have an average score o

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Question 1198946: Going into the final exam, which will count as two tests, Brooke has test scores 80, 83, 71, 61 and 95. What score does Brooke need on the final in order to have an average score of 80?
Here us my work:
Let x = final exam score
(80 + 83 + 71 + 61 + 95 + x)/6 = 80
Solving for x, I got 90. The textbook answer is 85.
What did I do wrong?
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
You must add x TWICE and divide by SEVEN.  You have counted the final exam
as if it only counted as one test, not two.

%2880%2B83%2B71%2B61%2B95%2Bx%2Bx%29%2F7=80

Solve that and you'll get the textbook answer.

Edwin