-
The average age of 5 sisters is 20 yr. If the age of the youngest sister be 4yr. What was the average age of the group of sister at the birth of the yongest sisiter ?
-
- 25 yr
- 15 yr
- 18 yr
- 20 yr
- None of the above
Correct Option: D
Total age of 5 sister = 20 x 5 = 100 yr.
4 yr ago, total sum of ages
= 100 - ( 5 x 4) = 100 - 20 = 80 yr
But at that time (4 yr ago), there were 4 sister in the group.
∴ Average age at that time(4 yr ago) = 80/4 = 20 yr.
