Examples on Averages 3
In this class, We discuss Examples on Averages 3.
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Example 1:
The average age of a husband and his wife was 23 years at the time of their marriage.
After five years, they have a one-year-old child. What is the average age of the family now?
Solution:
Given the average of husband and wife, we can identify the sum of the ages of husband and wife.
After identifying the sum of the ages of the husband and wife, we add five years to each.
Sum of ages of husband and wife at marriage = 23 * 2 = 46
Sum of ages of husband and wife now = 46 + 5* 2 = 56
Sum of ages of husband, wife, and child = 56 + 1 = 57 years.
The average age of the family = is 57/3 = 19 years.
Example 2:
The average age of a husband, wife, and child three years ago was 27 years.
The average age of the wife and the child five years ago was 20.
The present age of the husband is?
Solution:
From the first point in the question, we can identify the sum of the ages of the husband, wife, and child.
From the second point in the question, we can identify the sum of the ages of wife and child today.
Subtract the sum of the ages of husband, wife, and child with wife and child. We get the husband’s age.
Husband present age = sum of ages of husband, wife, and child – the sum of ages of wife and child
Sum of ages of husband, wife, and child now = (27*3) + (3*3) = 90 years
Sum of ages of wife and child now = (20 * 2) + (5*2) = 50 years
Husband age = 90 – 50 = 40 years.
Example 3:
Three years ago, the average family age of 5 members was 17.
A baby has been born. The average age of the family is the same today. What is the age of the baby?
Solution:
We need to identify the sum of the ages of the family with and without the baby.
Subtracting the sum of ages, we get the baby’s age.
Sum of ages of 5 members today = (17 * 5) + (5*3) = 100 years
Sum of ages of family with baby = 17 * 6 = 102
Baby age = 102 – 100 = 2 years