Find the median of the data in Example 3.2.

Array 17 22 28 31 31 31 32 32 33 37 37 39 39 39 40 42 44 45 In this case there are 18 observations, that is, n = 18, so:

Median position = (18 + 1)/2 = 9.5th Although we can find a ninth observation and a tenth observation there is clearly no 9.5th observation. The median position of 9.5th means that the median lies half-way between the ninth and tenth observations, 33 and 37, which appear in bold type in the array. To find the half-way mark between these observations, add them together and divide by two.