Calculate the mean of the following frequency distribution:

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$
Frequency	$12$	$16$	$8$	$6$	$8$

Midpoint (Midvalue) of the class $15-30$ is ........

Find the mean of the following frequency distribution:

Class	$21-25$	$26-30$	$31-35$	$36-40$	$41-45$	$46-50$	$51-55$
Frequency	$18$	$32$	$30$	$40$	$25$	$15$	$40$

(in $.675$)

The mean of the following frequency distribution is $43.75$. Find the missing frequency $f$.

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$	$80-90$	$90-100$
Frequency	$8$	$4$	$20$	$45$	$64$	$32$	$f$	$8$	$2$	$2$

Find the mean of the following frequency distribution:

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$
Frequency	$2$	$10$	$40$	$25$	$13$	$10$

(in $.7$)

The table below gives the percentage distribution of female teachers in the primary schools of rural areas of various states and union territories $(U.T.)$ of India. Find the mean percentage of female teachers by all the three methods discussed in this section.

Percentage of female teachers	$15$-$25$	$25$-$35$	$35$-$45$	$45$-$55$	$55$-$65$	$65$-$75$	$75$-$85$
Number of States/$U$.$T$.	$6$	$11$	$7$	$4$	$4$	$2$	$1$