When the outliers are removed, how does the mean change?

dot plot with 1 on 15, 1 on 23, 1 on 24, 1 on 26, 1 on 27, 1 on 35

the mean remains the same.
the mean decreases by 2.
the mean increases by 2.
there are no outliers.

In statistics, an outlier is an observation point that is distant from other observations.

Given the points
15, 23, 24, 26, 27 and 35

Notice, that the points 15 and 35 are distance from the other points and hence are outliers.

The mean of the observations including the outliers is given by


The mean of the observations without the outliers is given by


Therefore, when the outliers are removed, the mean remains the same.