The average marks of 60 students in a class are 62. The average marks of boys and girls in that subject are 60 and 65, respectively. The number of boys in the class is :

36

Lets assume

No. of Boys in the class = n

So, No. of girls in the class = 60 - n

As Average marks of the class will remain same

60 x 62 = 60 x n + 65 x (60 - n)

5n = 180

n = 36

No. of boys in the class are 36