Question

The following are the ages (years) of 5 people in a room:

14
,


24
,


24
,


20
,


24


A person enters the room.
The mean age of the 6 people is now 21.
What is the age of the person who entered the room?

Answer 1

let age of 6th person is x

sum of x = 14+24+24+20+24+x

= 106 + x

N = 6

mean = 21

now,

$mean = \frac{sum \: of \: x }{n} \\ 21 = \frac{106 + x}{6}$

$126 = 106 + x$

$x = 20$