There are 500 students in a school. The boys and girls are in the ratio 7 : 3. If 120 new girls are enrolled in the school, then what will be the ratio of the number of boys to that of girls?

Correct option is A

Given:

There are 500 students in a school.

Boys and girls are in the ratio 7:3.

Solution:

Let the number of boys =7x

The number of girls = 3x .
The total number of students is given by:
​$$7x + 3x = 500$$​​
 x = 50 
So, the number of boys =$$7 \times 50 = 350$$​​

The number of girls =$$3 \times 50 = 150$$​ .
After enrolling 120 new girls, the total number of girls becomes:
 150 + 120 = 270 
The new ratio of boys to girls is:
​$$\frac{350}{270} = \frac{35}{27}$$​​
Thus, the new ratio of boys to girls is 35:27 .