The A.M of $n$ observation is $ \overline x$ . If the sum of $ n-5$ observations is $a$, then the mean of remaining 5 observation is

Question

$\begin {array} {1 1} (A)\;\large\frac{n\overline x+a}{5} & \quad (B)\;\large\frac{n\overline x-a}{5} \\ (C)\;n\overline x +a & \quad (D)\;None \: of \: these \end {array}$