SOLUTION: A student's average on the first three tests of the semester was 75. If the final exam counts as much as two test grades, what must the student make on the final to have an averag

Question 25742: A student's average on the first three tests of the semester was 75. If the final exam counts as much as two test grades, what must the student make on the final to have an average of 80 or better in the class.
I know how to do average and everything and I tried taking the formula and plugging in what I had but I dont know what to do or even if what ive done was right. Any help with this would be greatly appreciated.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
test1 = T1
test2 = T2
test3 = T3
final = F
(T1 + T2 + T3)/3 = 75
that's what the problem says
solve for (T1 + T2 + T3)
(T1 + T2 + T3) = 3 x 75 = 225
also,
((T1 + T2 + T3) + F) / 5 = 80
I used 5 because the final coubts as two tests
(225 + F) / 5 = 80
225 + F = 400
F = 175
this is what the student must score on the final to average 80.
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