Question

There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was :
A) 20
B) 35
C) 54
D) 40

Answer 1

Q:

There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was :

A) 20
B) 35
C) 54
D) 40

Answer:   A) 20 

Explanation:

Numbers of students in section A = x 

∴ Numbers of students in section B and C = (100 – x) 

∴ x 70 + (100 – x) 87.5 = 84 100 

=> 70x + 87.5 100 – 87.5x = 8400 
=> 8750 – 17.5x = 8400 
=> 17.5x = 8750 – 8400
=> x = 20.