The average age of 5 members of a family is 21. If the age of grandfather is included, the average age is increased by 9 years. What is the age of grandfather?
The average age of 5 members of a family is 21. If the age of grandfather is included, the average age is increased by 9 years. What is the age of grandfather?
Explanation
Initial average age of 5 members = 21
Total age of 5 members = 21 * 5 = 105
New average age with grandfather = 21 + 9 = 30
Total age of 6 members (including grandfather) = 30 * 6 = 180
Age of grandfather = Total age of 6 members - Total age of 5 members
= 180 - 105
= 75
The correct answer is 75.