Question

This data contains six houses prices in Darwin.

$324 000 $289 000 $431 000 $295 000
$385 000 $1 700 000

A. Which price would be considered the outlier?
B. If the outlier was removed from the data set, by how
much would the median change?
(First work out the median for each case.)
C. If the outlier was removed from the data set, by how
much would the mean change, to the nearest dollar?
(First work out the mean for each case.)

Answer 1

A. The outlier in this data set is $1,700,000.

B. The median is the middle value of a data set. When the outlier is removed, the median is the average of the two middle numbers in the new data set. Without the outlier, the median is the average of $324,000, $289,000, $431,000, $295,000, and $385,000, which is $345,000. The median changes by $20,000.

C. The mean is the sum of all the values in a data set divided by the number of values. Without the outlier, the sum of the values in the data set is $324,000 + $289,000 + $431,000 + $295,000 + $385,000 = $1,724,000. There are five values in the data set without the outlier. Therefore, the mean without the outlier is $1,724,000 / 5 = $344,800. The mean changes by $111,200.