A) 74.4
B) 79.5
C) 81.2
D) 78.5
E) 72.5
Correct Answer: B
Solution :
By allegation method So, the ratio of students in Class A to B comes out to 3 : 4. And, the ratio of students in Class B to C is 4 : 5. Ratio of students in class A, B and C = 3 : 4 : 5 So, average of all the classes \[=\frac{(81\times 3+74\times 4+83\times 5)}{3+4+5}=\frac{243+296+415}{12}\] \[=\frac{954}{12}=79.5\]You need to login to perform this action.
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