Step: 1
The number of customers who visited the super market each hour are 15, 10, 12, 9, 18, 5, 8, 9, 15, 10 and 11.
Step: 2
The ascending order of the above data set is: 5, 8, 9, 9, 10, 10, 11, 12, 15, 15,18.
Step: 3
The least value in the above list of data is 5 and the greatest value is 18.
Step: 4
Middle quartile = median of the data = 10.
Step: 5
Lower quartile = median of lower half of the data = 9.
Step: 6
Upper quartile = median of upper half of the data = 15.
Step: 7
So, among the plots, plot 4 is the equivalent box-and-whisker plot for the data.
Correct Answer is : Plot 4