Given: The average age of 8 boys =16 years After adding the age of 1 more boy, the average age is increased by 1 year Concept used:
Average=
sum of observation
Total number of observation
Calculation: Sum of ages of 8 boys = 16 × 8 ⇒ 128 years After adding the age of the new boy, the average age becomes 17 years ⇒ Sum of ages after adding the new boy's age = 17 × 9 ⇒ 153 years The age of new boy = 153 - 128 = 25 years ∴ The age of the new boy is 25 years