To get the mean absolute deviation, we first need the mean of the set. The mean is calculated by the sum of the values divided by the number of data:
[tex]\begin{gathered} \mu=\frac{2+5+6+12+15}{5} \\ \mu=\frac{40}{5} \\ \mu=8 \end{gathered}[/tex]To get the means absolute deviation, we have to get the absolute difference between each data and the mean, sum them up and divide by the number of data:
[tex]\begin{gathered} d_1=|2-8|=|-6|=6 \\ d_2=|5-8|=|-3|=3 \\ d_3=|6-8|=|-2|=2 \\ d_4=|12-8|=|4|=4 \\ d_5=|15-8|=|7|=7 \\ MAD=\frac{6+3+2+4+7}{5}=\frac{22}{5}=4.4 \end{gathered}[/tex]