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

The formula to find the mean of a grouped data by the direct method is .........

If $Z = 36.8$ and $M = 33.6$,then $\bar{x} = \ldots \ldots \ldots \ldots .$

The mean of ungrouped data and the mean calculated when the same data is grouped are always the same. Do you agree with this statement? Give reason for your answer.

The following is the distribution of weights (in $kg$) of $40$ persons:

Weight (in $kg$)	$40-45$	$45-50$	$50-55$	$55-60$	$60-65$	$65-70$	$70-75$	$75-80$
Number of persons	$4$	$4$	$13$	$5$	$6$	$5$	$2$	$1$

Construct a cumulative frequency distribution (of the less than type) table for the data above.

For the calculations of mode of a grouped data,the maximum frequency of a class is denoted by $\ldots \ldots \ldots . .$