SSC MTS 6 Aug 2019 Shift 1 Paper

Given:
The average ages of (P, Q) = 13
The average ages of (Q, R) = 14
The average ages of (R, P) = 12
Concept:
We will be using the concept of average.
Formula used:
Average age = Total age / number of people
Calculation:
⇒ P + Q = 26 ---- (1)
⇒ Q + R = 28 ----(2)
⇒ R + P = 24 ---- (3)
From (1) + (2) + (3),
⇒ 2(P + Q + R) = 78
⇒ P + Q + R = 39 ---- (4)
From (4) - (3)
⇒ Q = 15 years
∴ The age of the Q is 15 years.