Step 1: Order the data (already done) Always start with data in ascending order 9, 11, 12, 13, 14, 15, 15, 16, 16 ???? Step 2: Find the median (Q2) There are 9 numbers an odd number. The median is the middle value (5th number). Median (Q2) = 14 Now the data is split in half: Lower half 9, 11, 12, 13 Upper half 15, 15, 16, 16 ???? Step 3: Find Q1 (lower quartile) Q1 = the median of the lower half. Lower half = 9, 11, 12, 13 median = average of 11 and 12 ???? 1 = ( 11 + 12 ) / 2 = 11.5 Q1=(11+12)/2=11.5 ???? Step 4: Find Q3 (upper quartile) Q3 = the median of the upper half. Upper half = 15, 15, 16, 16 median = average of 15 and 16 ???? 3 = ( 15 + 16 ) / 2 = 15.5 Q3=(15+16)/2=15.5 ???? Step 5: Find the IQR ???? ???? ???? = ???? 3 ???? 1 = 15.5 11.5 = 4 IQR=Q3Q1=15.511.5=4