XAT 2018 — QA & DI Question 12
RatioEasy
The number of boys in a school was 30 more than the number of girls. Subsequently, a few more girls joined the same school. Consequently, the ratio of boys and girls became 3:5. Find the minimum number of girls, who joined subsequently.
Answer & solution
- A
31
- B
51
52
- D
55
- E
Solution not possible
Solution
Let the number of girls in the school initially be ‘g’.
∴ Number of boys = g + 30.
If ‘x’ new girls who joined the school.
⇒ (g + 30)/(g + x) = 3/5
∴ 5g + 150 = 3g + 3x
∴ x = 2g/3 + 50
For x to be minimum g should be minimum. Also, g should be a multiple of 3 for x to be an integer.
⇒ Minimum value of g = 3
∴ The minimum value of x = 52.
Hence, option (c).