Question

The number of boys in a school is 400 more than the number of girls, if the total number of students is 680 find the number of girls

Answer 1

Answer:

Correct option is

A

20

As the ratio of boys to girls is 5:7 and the total number of students is 672,

Number of boys =

5+7

5

×672=280

And Number of girls =

5+7

7

×672=392

Let the number of boys admitted be a. Then total number of boys =280+a

As the number of girls increases by 8. total number of girls 392+8=400

Given, new ratio of boys to girls is 3:4

=>280+a:400=3:4

=>

400

280+a

=

4

3

On cross multiplying,

280+a=

4

3

×400

280+a=300

=>a=20

So, the number of new boys admitted is 20.

Answer 2

Answer:

140

Step-by-step explanation:

Let unknown be x=girls

No. of boys =x+400

x+x+400=680

2x+400=680

2x=680-400

2x=280

x=280/2

x=140

No. girls =140

No. boys=140+400=540

CHEKING:

540+140

=680