The male classmate is A, and the female classmate is 20% more than the male classmate.

So the female students are (1+20%) a =1.2a.

There are a+ 1.2a=2.2a people in the class.

The weight of the whole class is 48×2.2a= 105.6a kg.

Suppose the average weight of girls is X, and the average weight of boys is (1+20%) x =1.2x.

According to the meaning of the question:

1.2 ax+ 1.2 xa = 105.6 a

2.4x= 105.6

X = 44kg kg

So the average weight of boys is1.2x = 52.8kg..

So: the average weight of girls is 44kg.