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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

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.

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.