What happens to the mean of a set of numbers when a zero is added to the set?

Expert Answers

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When adding a zero to the numbers, the mean will get smaller.

Let us prove it by an example.

For example:

Let "2, 3, 5, 7, 9" be numbers that their mean is as follow.

m = (2+ 3 + 5+ 7+ 9) / total number

       = ( 26 / 5) = 5.2

The,n the mean = 5.2

Now if we add zero, the numerator will remain the same while the denominator will increase by 1:

Then the denominator will be greater, then the mean is smaller:

Let us calculate:

m = ( 2+ 3 + 5+ 7+  9 + 0)  / 6

     = ( 26)/6 =  4.333

==> m = 4.33

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