| Question | Average age of a group of 30 boys is 16 years. A boy of age 19 leaves the group and a new boy joins the group. If the new average age of the group is 15.8 years, find the age of the new boy. | |
| Type | multiple_choice | |
| Option | 12 years | incorrect |
| Option | 13 years | correct |
| Option | 14 years | incorrect |
| Option | 15 years | incorrect |
Total age of 30 boys = 30*16 = 480 years
As per question, if we minus age of boy who leaves the group and then add the age of boy who joins the group the new average becomes = 15.8 years.
=15.8
480 – 19 + X = 474
X = 474 – 480 +19
X = – 6 +19
= 13 years
