Find the mean deviation about the median for the following data; 3, 9, 5, 3, 12, 10, 18, 4, 7 , 19, 21

Here, the number of observations is11 which is odd. Arranging the data into ascending order, we get 3,3, 4, 5,7 ,9, 10, 12, 18, 19,21 Median =11+12th  or 6th  observation =9The absolute values of the respective deviations from the median  i.e., xi−M are: 6,6,5,4,2,0,1,3,9,10,12 Therefore, ∑i=111 xi−M=58 and M.D. (M)=111∑i=111 xi−M=111×58=5.27