There are x boys and y girls in this class. According to the meaning of the question:

85.5x+9 1y=(x+y)×88，

85.5x+9 1y=88x+88y，

85.5 x+9 1y-85.5 x = 88x+88y-85.5 x，

9 1y=2.5x+88y，

9 1y-88y=2.5x+88y-88y，

3y=2.5x，

So x: y = 3: 2.5 = (3× 2): (2.5× 2) = 6: 5;

The ratio of male to female in this class is 6: 5.