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	$6$	$10$	$5$	$6$	$4$	$2$	$2$

Consider the following frequency distribution:

Class	$0-5$	$6-11$	$12-17$	$18-23$	$24-29$
Frequency	$13$	$10$	$15$	$8$	$11$

The upper limit of the median class is

Find the median of the following frequency distribution:

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

During the medical check-up of $35$ students of a class,their weights were recorded as follows:

Weight (in kg)	Number of students
Less than $38$	$0$
Less than $40$	$3$
Less than $42$	$5$
Less than $44$	$9$
Less than $46$	$14$
Less than $48$	$28$
Less than $50$	$32$
Less than $52$	$35$

Draw a less than type ogive for the given data. Hence,obtain the median weight from the graph and verify the result by using the formula.

$A$ life insurance agent found the following data for the distribution of ages of $100$ policy holders. Calculate the median age,if policies are given only to persons having age $18$ years onwards but less than $60$ years.

Age (in years)	Number of policy holders
Below $20$	$2$
Below $25$	$6$
Below $30$	$24$
Below $35$	$45$
Below $40$	$78$
Below $45$	$89$
Below $50$	$92$
Below $55$	$98$
Below $60$	$100$

The following table gives the distribution of the lifetime of $400$ neon lamps:

Life time (in hours)	Number of lamps
$1500-2000$	$14$
$2000-2500$	$56$
$2500-3000$	$60$
$3000-3500$	$86$
$3500-4000$	$74$
$4000-4500$	$62$
$4500-5000$	$48$

Find the median lifetime of a lamp.