Q2 is the median, which is the middle number, which is 12
Q1 is the middle between the minimum and the median, which in this case is the middle between 6 and the second 12, which is both 9 and 10. so find the average (9+10/2) = 9.5
Q3 is the half way point between the median and the max, which is the second 12 and 24, 17 and 19 are the middle, once again find the average (17+19/2) which is 18
