Interquartile Range(IQR) Steps: 1: Put the numbers in order. 1, 2, 5, 6, 7, 9, 12, 15, 18, 19, 27. 2: Find the median. 1, 2, 5, 6, 7 , 9 , 12, 15, 18, 19, 27. 3: Place parentheses around the numbers above and below the median. Not necessary statistically , but it makes Q1 and Q3 easier to spot. (1, 2, 5, 6, 7), 9, (12, 15, 18, 19, 27). 4: Find Q1 and Q3 Think of Q1 as a median in the lower half of the data and think of Q3 as a median for the upper half of data. (1, 2, 5 , 6, 7) , 9 , ( 12, 15, 18 , 19, 27). Q1 = 5 and Q3 = 18. 5 Subtract Q1 from Q3 to find the interquartile range . 18 – 5 = 13. What if I Have an Even Set of Numbers? Example question : Find the IQR for the following data set: 3, 5, 7, 8, 9, 11, 15, 16, 20, 21. Step 1: Put the numbers in order . 3, 5, 7, 8, 9, 11, 15, 16, 20, 21. Step 2: Make a mark in the center of the data : 3, 5, 7, 8, 9, | 11, 15, 16, 20, 21. Step 3: Place...