5. The average age of a family of five members is the
same today as it was five years ago. There is no
change in the family, except the elder daughter being
replaced by the daughter-in-law. If the age of the
elder daughter is 48 years, how old is the daughter-
in-law? (in years)
Answers
Given:
Average age of a family of 5 is the same today as 5 years ago.
The daughter was in the family 5 years ago but left the family now.
The daughter-in-law was not in the family 5 years ago but joined the family now.
The daughter is 48 years old.
To Find:
The daughter-in-law age now.
Solution:
Define x:
Let their total age be x now.
Their total age 5 years ago is also x years old.
Find the total age that it would have increased over 5 years:
1 person = 5 years
5 people = 5 x 5
5 people = 25 years
Find the total age after 5 years if the family unit did not change:
Total age = x + 25
We know that the daughter has left:
Daughter = 48 years old
Total age without the daughter = x + 25 - 48
Total age without the daughter = x - 23
But we know that the total age did not change:
Total age without the daughter-in-law = x - 23
Total age with the daughter-in-law = x
Therefore, the daughter-in-law is 23 years old
Answer: The daughter-in-law is 23 years old
Answer:
the daughter in law is 23 years old