Question 21

# A group of three friends, K, L and M, are sitting in a cafe. Their average age is 24 years. Another friend ‘N’ joins the group and the new average age of the group becomes 23 years. If another friend ‘R’, whose age is 2 years more than that of ‘N’, replaces ‘K’, then the average age of L. M, N and R becomes 22.5 years. What is the age of K?

Solution

Average of K, L and M = 24
Sum of the age of K, L and M = 24 $$\times$$ 3 = 72
Average of K, L, M and N = 23
Sum of the age of K, L, M and N = 23 $$\times$$ 4 = 92
Age of N = 92 - 72 = 10
Age of R = 2 + Age of N = 2 +10 = 12
Average age of L, M, N and R = 22.5 years
Sum of age of L, M, N and R = 22.5 $$\times$$ 4 = 90
Sum of age of L, M and N = 90 - 12 = 78
Age of K = sum of the age of K, L, M and N - sum of age of L, M and N = 92 - 78 = 14

• Free SSC Study Material - 18000 Questions
• 230+ SSC previous papers with solutions PDF

##### Sonal Patel

2 years, 9 months ago

##### Soujanya

3 years, 1 month ago

92_72=20

##### Braj kishore

3 years, 2 months ago

Sir one doubt Age of N=92-72=20 bt how to 10?