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

Answer:

Explanation: Since 5 people have a mean age of 30, the sum of their ages is 5⋅30=150 . Adding one more person of age 36 to the group gives 6 people with sum of ages 150+36=186 . Now divide this by 6 to get the new mean for the group of 6 people: 1866=31 years.