Question

30 girls and boys have planned for a picnic. There is a ratio of 3 girls to 7 boys. How many boys are there?

Answer 1

given ratio of girls and boys =3:7
let the number of girls be 3x and boys be 7x
we know that the total number of boys and girls is 30 
thus,
3x+7x=30
10x=30
x=30/10
x=3
therefore ,the number of boys =7x=7(3)=21

Answer 2

Let The Common Multiple be x
So ratio of girls to boys = 3x : 7x

Total no . of Children = 30

According To The given Statement

3x + 7x = 30
10x = 30
x = 3

So,
No . of Girls = 3x = 3 * 3 = 9
No . of Boys = 7x = 7 * 3 = 21

Answer = No . Of Boys = 21

Check -
→No . of Boys + No . of Girls = 30
    9 + 21 = 30
→Ratio of Girls to the Boys = 3/7
    9/21 Dividing by 3 = 3/7

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