The following table gives the distribution of the life time of 400 neon lamps :

Lifetime (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.

$100$ surnames were randomly picked up from a local telephone directory and the frequency distribution of the number of letters in the English alphabets in the surnames was obtained as follows:

Determine the median number of letters in the surnames. Find the mean number of letters in the surnames? Also, find the modal size of the surnames.

Convert the above distribution to a less than type cumulative frequency distribution, and draw its ogive.

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

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

The following table gives production yield per hectare of wheat of $100$ farms of a village.