The average age of a group of 10 friends is 27 years. If one friend leaves the group, the average becomes 25 years. Find the age of the friend who left the group.

Correct option is A

Given:

The average age of 10 friends is 27 years.

When one friend leaves, the average age becomes 25 years.

Formula Used:

Average age =$$\frac{\text{Total Age}}{\text{Number of Friends}}$$​​

Solution:

The total age of 10 friends is:

​$$\text{Total Age} = \text{Average Age} \times \text{Number of Friends} = 27 \times 10 = 270 \, \text{years}$$​​

After one friend leaves, the average age becomes 25 for 9 friends:

​$$\text{Total Age (after one friend leaves)} = 25 \times 9 = 225 \, \text{years}$$​​

​$$\text{Age of the friend who left} = 270 - 225 = 45 \, \text{years}$$​​

Thus, the correct option is (a) 45 years