SOLUTION: Two algebra classes took the same test. The mean (average) of the first class of twenty students was 90 percent. The average of the second class was 75 percent. If the average g

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Question 50050: Two algebra classes took the same test. The mean (average) of the first class of twenty students was 90 percent. The average of the second class was 75 percent. If the average grade for the combined classes was 81 percent, how many students were in the second algebra class?
Answer by venugopalramana(3286) About Me  (Show Source):
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Two algebra classes took the same test. The mean (average) of the first class of twenty students was 90 percent.
HENCE TOTAL MARKS =20*90=1800
The average of the second class was 75 percent.
HENCE THEIR TOTAL = 75X...WHERE X IS THEIR STRENGTH.
If the average grade for the combined classes was 81 percent,
TOTAL FOR COMBINED CLASS=(X+20)*81=1800+75X
81X+1620=1800+75X
81X-75X=1800-1620=180
6X=180
X=30=NUMBER OF STUDENTS IN SECOND ALGEBRA CLASS
how many students were in the second algebra class?