The following are the ages (years) of 5 people in a room: 17, 21, 15, 15, 25
A person enters the room.
The mean age of the 6 people is now 25.
What is the age of the person who entered the room?

57 years

Step-by-step explanation:

The mean of a set of numbers is given as the ratio of the sum of the numbers to the number of numbers in the given data set.

Hence given that the age of 5 people are 17, 21, 15, 15, 25 and a 6th person joins the set, making the mean age 25, let the age of the new person that joined be x then

25 = (x + 17 + 21 + 15 + 15 + 25)/6

25 = (x + 93)/6

Multiply both sides by 6

150 = x + 93

subtract 93 from both sides

x = 150 - 93

x = 57 years

The age of the person who entered the room is 57 years

answer: .64

step-by-step explanation

set up the formula for standard deviation for this set of numbers, then simplify