SOLUTION: A class of 24 students took a test. The mean of the test scores for the whole class was 75 and the mean of the test scores for the 20 students who passed was 80. What was the mean

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Question 251776: A class of 24 students took a test. The mean of the test scores for the whole class was 75 and the mean of the test scores for the 20 students who passed was 80. What was the mean of the test scores for the students who did not pass? *Show Work!
Found 2 solutions by stanbon, richwmiller:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A class of 24 students took a test.
The mean of the test scores for the whole class was 75 and the mean of the test scores for the 20 students who passed was 80.
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Sum of points for those who passed was 20*80 = 1600
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What was the mean of the test scores for the students who did not pass?
Sum of points for the whole class as 24*75 = 1800
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Equation:
Mean of test scores for those not passing = (1800-1600)/(24-20) = 50
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Cheers,
Stan H.

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
let x=the average of the failing students
24-20=4 failing students
(4x+20*80)/24=75
1/24 (4 x+1600) = 75
x/6+400/6=75
multiply both sides by 6
x+400=75*6
x+400=(25*3)*(3*2)
x+400=(25*2)*(3*3)
x+400=50*9
x+400=450
x=50