Step: 1
Arrange the data values in increasing order.
3.5, 4.2, 4.7, 5.3, 5.8, 6.8, 12.5
Step: 2
Q2 = 5.3
[Q2 is the median, which is the middle value of the data set in the order.]
Step: 3
Q1 = 4.2
[Q1 is the median of the data values less than Q2.]
Step: 4
Q3 = 6.8
[Q3 is the median of the data values greater than Q2.]
Step: 5
Interquartile Range
(IQR) =
Q3 -
Q1
= 6.8 - 4.2 = 2.6
[Formula.]
Step: 6
To find the outlier, compute the cut-off points for outliers.
Step: 7
Lower fence =
Q1 - 1.5(
IQR)
= 4.2 - 1.5(2.6) = 0.3
[Formula.]
Step: 8
Upper fence = Q3 + 1.5(IQR)
= 6.8 + 1.5(2.6) = 10.7
Step: 9
If a data value is less than the lower fence or greater than the upper fence, then it is considered as an outlier.
Step: 10
The value 12.5 is greater than 10.7.
Step: 11
So, 12.5 is the outlier.