The $mean$ of $5$ observations is $5$ and their $variance$ is $124$. If three of the observations are $1, 2$ and $6$ ; then the mean deviation from the mean of the data is :

Question

$\begin{array}{1 1}(1)\; 2.4 \\ (2)\; 2.8 \\(3)\; 2.5\\ (4)\; 2.6 \end{array}$