Please help me find the population mean absolute deviation

Let a population consist of the values cigarettes, cigarettes, and cigarettes smoked in a day. Show that when samples of size 2 are randomly selected with

replacement, the samples have mean absolute deviations that do not center about the value of the mean absolute deviation of the population. What does this

indicate about a sample mean absolute deviation being used as an estimator of the mean absolute deviation of a population?

8 9 18

Calculate the mean absolute deviation for each possible sample of size 2 from the population.

Sample Mean Absolute Deviation

{8,8} 0

{8,9} 0.5

{8,18} 5

{9,8} 0.5

{9,9} 0

{9,18} 4.5

{18,8} 5

{18,9} 4.5

{18,18} 0

Calculate the population mean absolute deviation.

The population mean absolute deviation is .??

integer or decimal rounded to one decimal place as needed.)