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.
---
Sum of points for those who passed was 20*80 = 1600
---------------------------------------------
 
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
----------------------------------------------
Equation:
Mean of test scores for those not passing = (1800-1600)/(24-20) = 50
===========================
Cheers,
Stan H.