The excluding type of class $30-45$ does not include .........

For a given frequency distribution,the frequencies of the first,second,and third class are $8$,$15$,and $18$ respectively. Then,the cumulative frequency of the third class is $\ldots \ldots \ldots \ldots .$

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

The mean of the following frequency distribution is $18$. Find the missing frequency $f$.

Class	$11-13$	$13-15$	$15-17$	$17-19$	$19-21$	$21-23$	$23-25$
Frequency	$3$	$6$	$9$	$13$	$f$	$5$	$4$

Find the mean,median and mode of the following frequency distribution:

Class	$0-30$	$30-60$	$60-90$	$90-120$	$120-150$	$150-180$
Frequency	$8$	$15$	$16$	$20$	$12$	$9$

The median class of the following frequency distribution is ...........

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Frequency	$6$	$10$	$5$	$6$	$4$	$2$	$2$