Correct Answer - Option 3 : 1 : 1

Given:

The ratio of boys and girls in a college was 5 : 4. New students admitted and the number of boys went up by 20% and the number of girls went up by 50%

Calculation:

Let the number of boys and girls initially be 5x and 4x.

Hence, after new students admitted, number of boys = 5x × 120% = 6x

And, number of girls = 4x × 150% = 6x

New ratio of boys and girls = 6x : 6x = 1 : 1

∴ the correct answer is 1 : 1.