mean absolute deviation = ∑|(xₐ - mean )| ÷ n
where xₐ is every term in the data set
n is total number of terms
mean for the given data set = sum of all terms ÷ total number of terms =
130.9 ÷ 7 = 18.7
mean absolute deviation = ∑|(xₐ - mean )| ÷ n
mean absolute deviation == 23.6 ÷ 7 = 3.37
