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

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

Explanation

Five years ago, the average age of P and Q was 15 years.

This means that the total age of P and Q five years ago was 15 x 2 = 30 years.

Since then, both P and Q have aged 5 years, so their total age now is 30 + 5 + 5 = 40 years.

The average age of P, Q, and R today is 20 years, so the total age of P, Q, and R is 20 x 3 = 60 years.

We already know that the total age of P and Q is 40 years, so R's age must be 60 - 40 = 20 years.

After 10 years, R's age will be 20 + 10 = 30 years.

So, the correct answer is: 30 years