IQR is the difference between Q3 and Q1 so we first need to find those values. The data in order is: Lower half: 10.5, 11, 11.5, 14.5, Median (Q2) 14.5, Upper Half: 17, 17, 18, 19 Since both the upper and lower halves have an even number of data values we need to find the average between the two middle numbers. Q1 (11 + 11.5)/2 = 11.25 Q3 (17 + 18)/2 = 17.5 IQR = Q3 - Q1 = 17.5 - 11.25 = 6.25