Question

The average (arithmetic mean) of 5,10,15 and x is 20..What is the x ?

Answer 1

`Ave=(sum)/(count)`

`20=(5+10+15+x)/(4)`

`80=30+x`

`x=50`

Answer 2

x = 50 .

Explanation:

Given : Mean of 5,10,15 and x is 20.

To find : What is the x.

Solution : We have given Mean of 5, 10 , 15 and x is 20.

Mean = 20 .

Mean =
`(sum\ of \ data)/(Number\ of \ data)`.

Mean =
`(5+10+15 +x)/(4)`.

20 =
`(30 +x)/(4)`.

On multiplying both sides by 4

20 * 4 = 30 + x .

80 = 30 + x .

On subtracting both sides by 30.

50 = x

Therefore, x = 50 .