SSC GD 2019 PYQ — Question 57

SSC GD Constable (English) - 12 Feb 2019 Shift 2 • Quantitative Aptitude • Q57

If a 12 years old boy is replaced by a new boy, then the average age of 18 boys increases by 1.5 years. What is the age of the new boy?

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 39 years.

Understanding/Application

Average = Sum of all quantities/number of  quantities

Let the initial average x and the 12 year old boy is replaced by a new whose age is y.

ATQ-

18x - 12 + y = 18(x + 1.5)

18x - 12 + y = 18x + 27

y = 27 + 12 = 39