Question

in school 4/7student in boys.if 210 girls find the number of boys.​

Answer 1

I will use unitary method to solve this question. It is very easy and give you answer in less than 10 sec.

Here in 4/7 denominator always denotes total quantity

It in out of 7 unit, number of boys are 4 units

It is obvious that number of girls in 7 units are 3 units

It is also given 3 unit denotes 210 girls

So 1 unit denotes 70 girls

    7 unit denotes 490 girls and boys

    4 unit denotes 280 boys

If and doubt ask me.

Answer 2

In a school boys : girl = 4 : 7

=4/7

for girl,

=1-4/7

3/7x = 210

x = 210*7/3

x = 490

total student  = 490

girls = 490-210

= 280