In the formula $\bar{x} = A + \frac{\Sigma f_{i} d_{i}}{\Sigma f_{i}}$ for the mean,$d_{i} = \dots$

Consider the following distribution:

Marks obtained	Number of students
More than or equal to $0$	$63$
More than or equal to $10$	$58$
More than or equal to $20$	$55$
More than or equal to $30$	$51$
More than or equal to $40$	$48$
More than or equal to $50$	$42$

The frequency of the class $30-40$ is:

Consider the following frequency distribution of the heights of $60$ students of a class:

Height (in $cm$)	Number of students
$150-155$	$15$
$155-160$	$13$
$160-165$	$10$
$165-170$	$8$
$170-175$	$9$
$175-180$	$5$

The sum of the lower limit of the modal class and upper limit of the median class is:

For some given data,if $Z + M = 108$ and $Z - M = -6$,then the mean $\bar{x} = \ldots \ldots \ldots$

$\frac{Z-M}{M-\bar{x}}=\ldots \ldots \ldots \ldots$

If $M = 72$ and $\bar{x} = 70$,then $Z = \ldots \ldots \ldots \ldots$