Find the mean deviation of the set of numbers 4, 5, 9

A.
zero 
B.
2 
C.
5 
D.
6
Correct Answer: Option B
Explanation
x = (frac{sum x}{N})
= (frac{18}{3})
= 6
(begin{array}{cc} x & x – x & x – x \ hline 4 & 2 & 2\ 5 & 1 & 1\ 9 & 3 & 3\ hline & & 6end{array})
M.D = (frac{x – x}{N})
= (frac{6}{3})
= 2