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Change in the mean when a number is added

Find the change in the mean when a number is added

This math skill teaches how to find a number to add to a set of numbers in order to achieve a specific change in the mean. The process involves calculating the original mean, determining the desired mean, and then using these values to find the necessary number to add.

Learn change in the mean when a number is added

Teaching Transcript

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What number can we add to decrease the mean by 1?

Let's find our original mean. 9 plus 5 is 14, and 14 divided by 2 is 7, so our original mean is 7

It decreases by 1, so it will become 6

So we have 3 numbers with a mean of 6. That means they must add to 3 times 6, or 18

Our starting numbers add to 14, so our new number must be 4

Skill Practice

Find the change in the mean when a number is added

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