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Change in the mean when a number is changed

Find the change in the mean when a number is changed

This math skill teaches how to find the necessary change in one number of a set to achieve a specific decrease in the mean of the set. Adjusting the value of this number affects the sum, thereby changing the overall mean.

Learn change in the mean when a number is changed

Teaching Transcript

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Let's change the 10 to decrease the mean by 2

First we should find our original mean. The mean is the sum over the count, so our original mean is 9.

Which means our new mean will be 7.

If 4 numbers have a mean of 7, they must add up to 4 times 7, or 28. So 6 plus 14 plus 6 plus our new number equals 28.

So 10 must change to 2 to reduce the mean by 2

Skill Practice

Find the change in the mean when a number is changed

Test your understanding of change in the mean when a number is changed by practicing it! Work through the below exercises to use it in practice.