The ratio of the number of boys to the number of girls in a class is 2 5 If 10 boys leave the class ...........

Quantitative Aptitude (MTS) Ratio, Proportion

The ratio of the number of boys to the number of girls in a class is 2 : 5. If 10 boys leave the class and 20 new girls join the

class, then the new ratio of boys and girls in the class becomes 4 : 25. What is the number of boys in the class now?

This questions was previously asked in

SSC MTS 22nd July 2022 Shift-1

- Initially, the ratio of boys to girls is 2:5. Let the number of boys be 2x and the number of girls be 5x.

- When 10 boys leave, the number of boys is 2x - 10.

- When 20 new girls join, the number of girls is 5x + 20.

- The new ratio is given as 4:25.

- Set up the equation: (2x - 10) / (5x + 20) = 4 / 25.

- Cross-multiply to solve for x: 25(2x - 10) = 4(5x + 20).

- Simplify: 50x - 250 = 20x + 80.

- Solve: 30x = 330, so x = 11.

- Find the current number of boys: 2x - 10 = 2(11) - 10 = 12.

- Option:1, 12 is the correct answer.

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