Question

There are 420 children in a school. 45% of the pupils are boys.

How many boys are there?
How many girls are there?

Answer 1

total children = 420
boys = 45% of 420 = 189 boys
Girls = (100-45)% = 55% of 420 = 231 boys

Answer 2

`1 \% = (1)/(100) \\ \\ 45 \% =(45)/(100)=(9)/(20)\\ \\ total \ children : 420 \\ \\ boys : \\ \\420 \cdot 45 \% = 420 \cdot (9)/(20)= 21\cdot 9 =189 \\ \\ girls : \ \\ \\ 420 -189 = 231`