The ratio of boys and girls in a school of 720 students is 3 : 5. If 18 new girls are admitted, then how many new boys can be admitted in the school so that the ratio of boys and girls becomes 2 : 3?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 42.
Calculations:
In a school of 720 students, the ratio of boys to girls is 3 : 5.
Number of boys = 3/8 × 720 = 270
Number of girls = 720 - 270 = 450
Let the number of new boys be x
⇒ (270 + x)/(450 + 18) = 2/3
⇒ 3(270 + x) = 2 × 468
⇒ 810 + 3x = 936
⇒ 3x = 936 - 810
⇒ 3x = 126
⇒ x = 42
Hence, the number of new boys can be admitted in the school = 42