The values that divide a list of numbers into quarters.
In {2, 4, 4, 5, 6, 7, 8} :
· Quartile 1 (Q1) = 4
· Quartile 2 (Q2), which is also the Median, = 5
· Quartile 3 (Q3) = 7
Q1, Q2, and Q3 are the 25th, 50th, and 75th percentiles, respectively,