Question

Mean deviation of the series a, a + d, a + 2d, a + 2nd from its mean is

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

$\overline{x}=\frac{\frac{2n+1}{2}(a+a+2nd))}{(2n+1)}=a+nd\sum |x-\overline{x}|=2d(1+2+.....+n)=n(n+1)d\therefore M.D=\frac{n(n+1)d}{(2n+1)}$