SOLUTION: Thirty students took a test.The average grade for the whole class was 70 and the average of the twenty who passed was 80.What was the average of the one who failed?

Question 705081: Thirty students took a test.The average grade for the whole class was 70 and the average of the twenty who passed was 80.What was the average of the one who failed?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Thirty students took a test.
The average grade for the whole class was 70 and the average of the twenty who passed was 80.
What was the average of the one who failed?
:
f = the average of the 10 that failed
= 70
multiply both sides by 30
10f + 1600 = 30(70)
10f = 2100 - 1600
10f = 500
f = 500/10
f = 50 is the av of the 10 that failed
:
:
Check this
= 70

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