Given a frequency distribution table of marks, calculate the mean and variance.

To solve this problem, we first need to calculate the midpoint ($x$) for each class interval, and then use these values along with the frequencies ($f$) to compute the necessary sums.

Step 1: Create a summary table for calculations.

Marks	No of Students ($f$)	Midpoint ($x$)	$fx$	$x^2$	$fx^2$
0-10	16	5	80	25	400
10-20