Question

The number of boys and girls in a class are in the ratio 7:5 the number of boys is 8 more than the number of girls what is the total strength of class.....



Fifteen years from now Ravi's age will be 4 times his present age what is Ravi's is present age.......



Answer this plzz

Answer 1

Answer 1:

Boys : Girls = 7 : 5

Let the no. of Boys be 7x and No. of girls be 5x

It is given that there are 8 more boys than girls
This means that

7x - 5x = 8

2x = 8

x = 4

Now,

No. of Boys = 4 × 7
No. of Boys = 28

No. of Girls = 4 × 5
No. of Girls = 20


Total Students = 28 + 20

Total Students = 48
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ANSWER 2)..
Let ravi's present age = r
ravi's age 15 years later = r + 15 = 4r
so 15 = 4r - r
15 = 3r
15/3 = r
5 =r
so ravi's present age = 5
ravi's present age + 15 =20
20 = 4r
r = 5


Hope it helps:')

Answer 2

According to given sum,

1) Ratio of no.of boys to no. of girls => 7:5

let the no.of girls be x. Then the no. of boys will be (x+8).

From the question,

x+8:x = 7:5

$= > \frac{x + 8}{x} = \frac{7}{5}$

$= > \: 5(x + 8) = 7x$

$= > \: 5x + 40 = 7x$
$= > \: 2x = 40$

$= > \: x = 20$

so, the number of girls are 20.

And no. of boys are (20+8) => 28.

so, total strength of the class => 20+28 => 48

2) let the Ravi's present age be x.

Age of Ravi after 15 years => x+15.

From the question,

x+15 = 4x

=> 3x= 15.

=> x= 5

so, the present age of Ravi is 5 years.

:-)Hope it helps u.