Write mid-value of the following frequency distribution.

Class interval	$8-11$	$12-15$	$16-19$	$20-23$	$24-27$	$28-31$	$32-35$
Frequency	$4$	$4$	$5$	$13$	$20$	$14$	$8$

$$

Find the mode of the following data.

Write mid-value of the following frequency distribution.

Find the median of the following data.

$\mathrm{X}-$coordinate of intersecting point of two ogives, represents

The mode of the data $5,6,9,10,6,11,4,6,10,4$ is _____

The letter that represents $\frac{x_i-a}{h},$ which is used in measuring mean is _____