IXL | Mean: find the missing number

Janet has the following data:

If the mean is 9, which number could x be?

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Learn with an example

Reggie has the following data:

If the mean is 12, which number could x be?

The mean is the average of the numbers. You find the mean by adding the numbers together and then dividing by the number of numbers in the group.

There are 4 numbers in the group.

Try x = 13.

Find the sum of the numbers.

13 + 16 + 15 + 16 = 60

Divide by 4.

60 ÷ 4 = 15

When x = 13, the mean is 15.

Try x = 1.

Find the sum of the numbers.

1 + 16 + 15 + 16 = 48

Divide by 4.

48 ÷ 4 = 12

When x = 1, the mean is 12.

The mean is 12, so x = 1.

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