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The average of your first three test gra...

The average of your first three test grades is 78. what grade must you get on your fourth and final test to make your average 80?

A

80

B

82

C

84

D

86

Text Solution

Verified by Experts

The correct Answer is:
D
since the average of your first three test grades is 78, each test grade could have been a 78. if x represents you final test grade, the average of the four test grades is `(78+78+78+x)/(4)`. Which is to be equal to 80. therefore, `(234+x)/(4)=80`.
`234+x=320.` so x=86.
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