Question

The ratio of boys and girls in a class is 5 ∶ 3. In next year, the number of boys increased by 25 and the number of girls increased by M. Now, their ratio became 9 ∶ 5. Find the value of M.
1. 42
2. 28
3. 38
4. 52
5. Can't be determined

Answer 1

Correct Answer - Option 5 : Can't be determined

Given:

The ratio of boys and girls = 5 ∶ 3

In next year, the ratio of boys and girls = 9 ∶ 5

Formula:

New ratio of boys to girls = number of boys after increment/number of girls after increment

Calculation:

Let the number of boys is 5x and number of girls is 3x

In new year, the number of boys increased by 25 and the number of girls increased by M,

⇒ (5x + 25)/(3x + M) = 9/5

⇒ 25x + 125 = 27x + 9M

⇒ 2x + 9M = 125

There are two variables and one equation. The value of M cannot be determined.

∴The value of M cannot be determined.