Question

Draw a 'less than' ogive from the following data and hence find out the value of Median.

Class	20-25	25-30	30-35	35-40	40-45	45-50	50-55	55-60
Frequency	6	9	13	23	19	15	9	6

Answer 1

For constructing a less than ogive, first the given frequency distribution is converted into a less than cumulative frequency distribution as follows:

Class	Frequency (f)	Cumulative Frequency (c.f.)
Less than 25 Less than 30 Less than 35 Less than 40 Less than 45 Less than 50 Less than 55 Less than 60	6 9 13 23 19 15 9 6	6 15 28 51 70 85 94 100

We now plot the cumulative frequencies against the upper limit of the class intervals. The curve obtained on joining the points so plotted is known as the less than ogive.


Hence, median is 39.78.