Question

In a class of 100 students, there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class is 72, then what is the average of the girls?

(a) 73

(b) 65

(c) 68

(d) 74

Answer 1

The correct option is (b) 65.

Explanation:

Since, total number of students = 100 

and number of boys = 70 

Number of girls = (100 - 70)= 30

Now, the total marks of 100 students = 100 x 72 = 7200

And total marks of 70 boys = 70 x 75 = 5250

Total marks of 30 girls = 7200 - 5250 = 1950

Average marks of 30 girls = 1950/30 = 65