xi fi c.f. |xi - | fi|xi - | 15 3 3 |15-30|=15 45 21 5 8 |21-30|=9 45 27 6 14 |27-30|=3 18 30 7 21 |30-30|=0 0 35 8 29 |35-30|=5 40 Total 29 148 N = 29(odd), which is an odd number, therefore Median observation = Hence, Median = 30 Mean Deviation (M) =