Question

This data set represents the number of cups of coffee sold in a café between 8 a.m. and 10 a.m. every day for 14 days.

Answer 1

4 days gives us 14 numbers to play with a quartile is 1/4 of the data set (by count). so 1q = 14/4 sort the numbers from small to large and find the 1q and 3q values

Answer 2

The interquartile range (IQR) is the difference between quartile 3 and quartile 1. In this data set the IQR = 6

4,5,6,6,7,8,9,9,10,10,12,12,14,15

Q1 = 6
Q2 = 9
Q3 = 12

IQR =  Q3 - Q1 = 12 - 6 = 6