The average age of 5 members of a family is 20 years. If a new member joins the family, the average age becomes 18 years. What is the age of the new member?

Correct option is C

Given
Initial number of members = 5
Initial average age = 20 years
New average age after 1 member joins = 18 years

Formula Used
Total Age =  $$Average\ Age \times Number \ of \ Members$$​​
Age of new member = New Total Age - Old Total Age

Solution
Old total age of 5 members = $$5 \times 20$$​ = 100 years
New total age of 6 members = $$6 \times 18$$​ = 108 years
Age of the new member = 108 - 100 = 8 years
Final Answer
So the correct answer is (c)