Question

The mean age of 5 people in a room is 40 years. A person enters the room. The mean age is now 35. What is the age of the person who entered the room?

Answer 1

`\boxed{\sf \ \ \ 10 \ y\ old \ \ \ }`

Explanation:

Hello,

let s note a, b, c, d, e the age of the 5 people

we can say that

`(a+b+c+d+e)/(5)=40`

So
`a+b+c+d+e=5*40=200`

Now there is another person , let s note his age x

we can write

`(a+b+c+d+e+x)/(6)=35\\<=> a+b+c+d+e+x=6*35=210\<=> x = 210 - (a+b+c+d+e)`

but we know that a+b+c+d+e = 200 so

x = 210 - 200 = 10

hope this helps

Answer 2

10 years.

Explanation:

Let total age of five people be x;

x/5 = 40

x = 40*5

x = 200.

Let age of new person be y;

(200 + y)/ 6 = 35

200 + y = 210

y = 210-200

y= 10.

The age of the new person is 10.

See ya!

Hope it helps!