Question

The average age of five brothers is 20 years. If the age of their mother is included then, the average increases by 10 years. The age of the mother is
1. 60 years
2. 70 years
3. 90 years
4. 80 years

Answer 1

Correct Answer - Option 4 : 80 years

Given:

The average age of 5 brothers = 20 years

Concept used:

Average is the central value of a given set of values.

Formula Used:

Average = (Sum of terms/Number of terms)

Calculation:

As the average age of 5 brothers = 20 years

Sum of the age of 5 brothers = 20 × 5 = 100 years

As, when age of mother was included

New average = (20 + 10) = 30 years

Sum of the ages of 5 sons and mother = 30 × 6 = 180 years

⇒ Age of mother = 180 - 100 = 80 years

∴ The age of the mother is 80 years.