Correct Answer - Option 2 : 1500

**Given:**

The ratio of number of boys and girls = 5 : 7

In the next session, 250 boys and 450 girls joined

**Calculation:**

Let the ratio of boys and girls be 5x : 7x

According to the question

\(\dfrac{5x \ + \ 250}{7x \ + \ 450} = \dfrac{2}{3}\)

⇒ 15x + 750 = 14x + 900

⇒ x = 150

The number of girls now

7 × 150 + 450 = 1500

**∴ The number of girls now is 1500.**