The average age of students in a school is 16.2 years. The average age of boys is 17.4 years and that of girls is 15.2 years. The ratio of the number of boys to that of girls is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 5:6
Let boys = x, girls = y
(17.4x + 15.2y) / (x + y) = 16.2
⇒ 17.4x + 15.2y = 16.2x + 16.2y
⇒ 17.4x - 16.2x = 16.2y - 15.2y
⇒ 1.2x = 1.0y
⇒ x / y = 5 / 6