Five years ago, the average age of P and Q was 15 years. Now, the average age of P, Q and R is 20 years. What would be the age of R after 10 years?

by

A. 30 year 
B. 20 year
C. 35 year
D. 25 year

🧠 Explanation (Math):

Given: 5 years ago, average(P,Q) = 15; now average(P,Q,R) = 20
Step 1: 5 years ago sum(P,Q) ÷ 2 = 15 ⇒ sum(P,Q) then = 30
Step 2: Add back 5 years to each: current sum(P,Q) = 30 + 10 = 40
Step 3: Now (P + Q + R)/3 = 20 ⇒ P + Q + R = 60
Step 4: Substitute P + Q = 40 ⇒ R (now) = 60 − 40 = 20
Step 5: After 10 years, R = 20 + 10 = 30
Final Answer: 30 year