First order the numbers from least to greatest.
8,12,31, 45, 45,47, 48, 51,55
Min: 8
Q1: 21.5
Q2: 45
Q3: 49.5
Max: 55
To find Q1 find the average of the lower half. (12 + 31)/2
43/2 = 21.5
To find Q3 find the average of the upper half.
(48+51)/2= 49.5
