If $Z - M = 4$,then $M - \bar{x} = \dots$

In a maths test taken by $40$ students,the average score of $30$ boys is $16$ and the average score of $10$ girls is $12$. Which of the following gives the average score of the whole class?

If $Z+M=34$ and $M+\bar{x}=40,$ then $M=\ldots \ldots \ldots . . .$

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

Weekly income of $600$ families is tabulated below:

Weekly income	Number of families
$0-1000$	$250$
$1000-2000$	$190$
$2000-3000$	$100$
$3000-4000$	$40$
$4000-5000$	$15$
$5000-6000$	$5$
Total	$600$

Compute the median income (in $Rs.$).

The abscissa of the point of intersection of the less than type and of the more than type cumulative frequency curves of a grouped data gives its