$Z - \bar{x} = \dots \times (M - \bar{x})$

Find the median of the following frequency distribution:

Class	$5-10$	$10-15$	$15-20$	$20-25$	$25-30$	$30-35$	$35-40$	$40-45$
Frequency	$5$	$6$	$15$	$10$	$5$	$4$	$2$	$2$

For some given data,if $Z - M = 2$ and $\bar{x} = 33.5$,then $Z = \ldots \ldots \ldots$ (in $.5$)

$\Sigma(x_{i} - \bar{x}) = \ldots \ldots \ldots$

Calculate the mean of the scores of $20$ students in a mathematics test:

Marks	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$
Number of students	$2$	$4$	$7$	$6$	$1$

For a given frequency distribution,$\Sigma f_{i} d_{i} = -50$,$\Sigma f_{i} = 200$ and $A = 62.5$. Then the mean $\bar{x} = $ ........