Now if this had been a population.

In other words, the bus only ran eight times in total.

It's never going to run again, ever.

It's the entire population.

Then the equation would be slightly different.

We'd use the symbol sigma for the standard deviation.

And the equation would be one over n, where n is the total number.

Times the summation of xi minus mu.

Where mu is the average of the entire population.

But the average, of course, is just the same.

Mu is equal to x bar here.

So, in this case,

the equation becomes one over eight, multiplied by the same parenthesis.

And the answer is then a little bit different, it's equal to 2.52.

But, of course, if n, either lower case n, becomes a very big number.

Then the standard deviation of the sample

becomes essentially equal to the standard deviation of the entire population.

When n is a big number.