Example

raw data:

31 28 28 30 20
25 38 40 26 28
15 21 28 36 25
16 21 34 37 30
23 24 36 32 25

Again, sort it from least to greatest.

Q1 is 25 percentile Q2 is 50 percentile Q3 is 75 percentile

Box and Whisker plot