Question

The mean age of 5 people in a room is 31 years.

A person enters the room.
The mean age is now 30.
What is the age of the person who entered the room?

Answer 1

25

Explanation:

1. the sum of all the ages of the 5 people is 31 X 5 which is 155.

2. when the new person is added the sum becomes 30 X 6 which is 180.

3. the difference between 180 and 155 is 25.

4. this means that 25 is the age of the person who entered the room.