If the age of the youngest member be 7 years, the average age of the family at the birth of the youngest member was?

Question

The average age of a family of 6 members is 22 years. If the age of the youngest member be 7 years, the average age of the family at the birth of the youngest member was?

Answer 1

Average of 6 family members=22
sum of the ages of 6 family members=22*6=132
Age of the youngest member=7
sum of the ages of 5 family members excluding youngest member=132-7=125
After the birth of youngest member each family member's age is increased by 7.
Sum of increase in each member's age after the birth of youngest member=5*7=35
7 years before ,sum of the ages of 5 family members excluding youngest member=125-35=90
the average age of the family at the birth of the youngest member =90/5=18