Question

If outlier is removed from the data set $5,8,3,9,7,4,27$
The mean of the dataset .

• A. will increase
• B. will decrease
• C. will be same

Answer 1

The correct option is B will decrease

In the given data set, $27$ is an outlier.

The mean of data set with outlier is
$(5+8+3+9+7+4+27)/7$$=63/7=9$

The mean of the data set without oulier is
$(5+8+3+9+7+4)/6$$=36/6=6$

We can see on excluding outliers, the mean value of the dataset decreased.

$\therefore$ Inclusion of outlier in a dataset always changes the mean value of the data set.