SOLUTION: a students needs to average 80 on her tests in order to earn a B in her math class. Her average afterr 4 tests is 77.5 What score is needed on the fifth test in order to raise the

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Question 510403: a students needs to average 80 on her tests in order to earn a B in her math class. Her average afterr 4 tests is 77.5 What score is needed on the fifth test in order to raise the average to 80?
Answer by Maths68(1474) About Me  (Show Source):
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Total of 4 tests
===============
Average = 77.5
Total = x
Number of tests = 4
Total/Number of test = Average
x/4=77.5
x=77.5*4
x=310

Average of 5 test
===============
Socre in fifth test = y
Average needed = 80
Total = x+y (score in all 4 tests + score in 5th test)
Number of tests = 5
Total / Number of test = Average needed
(x+y)/5=80
(310+y)/5=80
310+y=80*5
310+y=400
y=400-310
y=90
Student has to score 90 in 5th test in order to raise the average to 80.