NCHMCT JEE 2010 Question Paper with solutions for online practice

Let there are x boys and y girls.
Average age of class = 15.8 yr
Total age of class = 15.8 (x + y) yr
Average age of boys = 16.4 yr
Total age of boys = 16.4x yr
Average age of girls = 15.4 yr
Total age of girls = 15.4y yr
Hence, 15.8(x + y) = 16.4x + 15.4y
⇒ 15.8y – 15.4y = 16.4x – 15.8x
⇒ 0.4y = 0.6x
⇒

x

y

=

2

3