SOLUTION: In a particular course a student's semester grade is determined by the average of five hour tests. On her first four hour tests, a student's grades were 82 81 82 and 75. If her sem

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Question 156391: In a particular course a student's semester grade is determined by the average of five hour tests. On her first four hour tests, a student's grades were 82 81 82 and 75. If her semester average turned out to be 82, what did she get on her fifth exam?
Found 2 solutions by Alan3354, Earlsdon:
Answer by Alan3354(69443) About Me  (Show Source):
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In a particular course a student's semester grade is determined by the average of five hour tests. On her first four hour tests, a student's grades were 82 81 82 and 75. If her semester average turned out to be 82, what did she get on her fifth exam?
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The average 82 is the sum divided by 5. So 82 = sum/5. Sum = 82*5 = 410.
The other 4 add up to 320, so the 5th one is 410-320, = 90.

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
The average of a set of numbers is the sum of the numbers divided by the number of numbers added up.
Let x = the grade of the fifth exam, so we add the grades of the first four tests to the grade on the fifth test (x) and divide this by the total number of test taken (5), and this is to be equal to her semester average of 82.
%28x%2B82%2B81%2B82%2B75%29%2F5+=+82 Add the known scores and then multiply both sides by 5.
x%2B320+=+410 Subtract 320 from both sides.
x+=+90
She must have obtained a score of 90 on her fifth test.