Question

The mean of four numbers is 30. If three of the numbers are 12, 50, 48, what is the fourth number?

Answer 1

\[\frac{12+50+48+?}{4}=30\]

Answer 2

@iGreen

Answer 3

Follow @satellite73 's equation.

\[\frac{12+50+48+x}{4}=30\]

First we can add up 12 + 50 + 48, what do you get?

Answer 4

110 @iGreen

Answer 5

Yes, so we have:

\(\dfrac{110+ x}{4} = 30\)

Now we multiply 4 to both sides, what's 30 * 4?

Answer 6

120

Answer 7

Yes, so we have:

\(110 + x = 120\)

Now subtract 110 to both sides.

Answer 8

10?? @iGreen

Answer 9

Yep, you got it.

Answer 10

x = 10

Answer 11

Thx