So we want to find the MAD of the data set {5,12,1,6,11}. To do that first we need to find the mean value X. X=(5+12+1+6+11)/5=35/5=7. Now we have to find the distance d from the mean value for every number in the data set: d1=7-5=2, d2=12-7=5, d3=7-1=6, d4=7-6=1, d5=11-7=4. Now we can find the MAD: MAD=(2+5+6+1+4)/5=18/5=3.6