Calculate the median, which is the middle number of an ordered range with an odd number. 3.
Calculate the medians of the bottom and top halves, omitting the middle number. Since these are now even-numbered sets, we'll take the average of the middle two numbers of each. Lower is 1.5, upper is 4.5.
Calculate the difference of the upper median and lower median, so 4.5 - 1.5 = 3.
