Question

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

Answer 1

Answer:

x = 50 .

Step-by-step 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 = $\frac{sum\ of \ data}{Number\ of \ data}$.

Mean = $\frac{5+10+15 +x}{4}$.

20 = $\frac{30 +x}{4}$.

On multiplying both sides by 4

20 * 4 = 30 + x .

80 = 30 + x .

On subtracting both sides by 30.

50 = x

Therefore, x = 50 .

Answer 2

$Ave=\frac{sum}{count}$
$20=\frac{5+10+15+x}{4}$
$80=30+x$
$x=50$