SOLUTION: In a school of three classes pupils took the same examination. Class A contain 30 pupil and the average mark for the class was 66 , class b contains 22 pupil and the average mark w

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Question 1125572: In a school of three classes pupils took the same examination. Class A contain 30 pupil and the average mark for the class was 66 , class b contains 22 pupil and the average mark was 54, class c contain 20 pupil, the average mark obtained by all pupils In the school was 61.5, calculate the average mark for class c. Please help me I tried but im stuck I can send a picture of what I did so far.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
In a school of three classes pupils took the same examination.
Class A contain 30 pupil and the average mark for the class was 66 ,
class b contains 22 pupil and the average mark was 54,
class c contain 20 pupil,
the average mark obtained by all pupils in the school was 61.5,
calculate the average mark for class c.
:
Total students in the 3 class 30+22+20 = 72
let x = the average of class c
:
%2830%2866%29+%2B+22%2854%29+%2B+20x%29%2F72 = 61.5
1980 + 1188 + 20x = 72(61.5)
you should be able to solve this now