Answer
IQR = Q3 - Q1
Upper fence value = Q3 + (1.5×IQR)
Work Step by Step
a.) Rearrange the values in ascending order : 4.1, 5.2, 6.8, 7.3, 7.4, 7.8, 7.8, 8.4, 8.7, 9.7, 9.9, 10.6, 10.7, 11.9, 12.7, 14.2, 14.5, 18.8
The median or Q2 =(8.7 + 9.7)/2 = 9.2
Median of Lower Half Observations, Q1 = 7.4
Median of Upper Half Observations, Q3 = 11.9
b.) IQR = Q3 - Q1
= 11.9 - 7.4
= 4.5
c.) Upper fence value = Q3 + (1.5×IQR)
= 11.9 + (1.5×4.5)
= 18.65
d.) see attached link
