The mode of the observations $4, 5, 6, 3, 4, 3, 3, 2, 3, 5$ is $\ldots \ldots \ldots \ldots .$

The mean of the following frequency distribution is $28.5$ and the total frequency is $60$. Find the missing frequencies $f_{1}$ and $f_{2}$.

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$
Frequency	$6$	$f_1$	$20$	$15$	$f_2$	$4$

Find the median of the following frequency distribution:

Class	$30-35$	$35-40$	$40-45$	$45-50$	$50-55$	$55-60$	$60-65$	$65-70$	$70-75$
Frequency	$1$	$2$	$5$	$10$	$17$	$15$	$9$	$5$	$3$

The following is the cumulative frequency distribution (of less than type) of $1000$ persons each of age $20$ $years$ and above. Determine the mean age.

Age (years)	$30$	$40$	$50$	$60$	$70$	$80$
Cumulative Frequency	$100$	$220$	$350$	$750$	$950$	$1000$

Construct the cumulative frequency distribution of the following distribution:

Class	$12.5-17.5$	$17.5-22.5$	$22.5-27.5$	$27.5-32.5$	$32.5-37.5$
Frequency	$2$	$22$	$19$	$14$	$13$

The weights (in $kg$) of $50$ wrestlers are recorded in the following table:

Weight (in $kg$)	$100-110$	$110-120$	$120-130$	$130-140$	$140-150$
Number of wrestlers	$4$	$14$	$21$	$8$	$3$

Find the mean weight of the wrestlers (in $kg$).