For a given frequency distribution,$n=100, A=15$ and $\bar{x}=15$. Then,$\Sigma f_{i} d_{i} = \ldots$

The mean of the following data is $26.5$ and the total frequency is $60$. Find the missing frequencies $x$ and $y$.

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$
Frequency	$6$	$x$	$17$	$y$	$8$

For a given frequency distribution,$\bar{x} = 19.7$,$A = 20$,and $n = 50$. Then,$\Sigma f_{i} d_{i} = \ldots$

Consider the following distribution:

Marks obtained	Number of students
More than or equal to $0$	$63$
More than or equal to $10$	$58$
More than or equal to $20$	$55$
More than or equal to $30$	$51$
More than or equal to $40$	$48$
More than or equal to $50$	$42$

The frequency of the class $30-40$ is:

Find the median of the following frequency distribution:

Class	$0-20$	$20-40$	$40-60$	$60-80$	$80-100$
Frequency	$5$	$15$	$20$	$18$	$2$

The frequency distribution table of agricultural holdings in a village is given below:

Area of land (in hectares)	$1-3$	$3-5$	$5-7$	$7-9$	$9-11$	$11-13$
Number of families	$20$	$45$	$80$	$55$	$40$	$12$

Find the modal agricultural holdings of the village (in hectares).