Using the data given below construct the cumulative frequency table and draw the ogive. From the ogive, determine the median.

Marks	No. of students
0 - 10	3
10 - 20	8
20 - 30	12
30 - 40	14
40 - 50	10
50 - 60	6
60 - 70	5
70 - 80	2

1. The cumulative frequency table for the given continuous distribution is :

2. Take 1 cm along x-axis = 10 marks

3. Take 1 cm along y-axis = 10 (students)

4. Plot the points (10, 3), (20, 11), (30, 23), (40, 37), (50, 47), (60, 53), (70, 58) and (80, 60) representing upper class limits and the respective cumulative frequencies.
   Also plot the point representing lower limit of the first class i.e. 0 - 10.

5. Join these points by a freehand drawing.

The required ogive is shown in figure above.

Here, n (no. of students) = 60.

To find the median :

Let A be the point on y-axis representing frequency = $\dfrac{n}{2} = \dfrac{60}{2}$ = 30.

Through A draw a horizontal line to meet the ogive at P. Through P, draw a vertical line to meet the x-axis at M. The abscissa of the point M represents 35 marks.

Hence, the required median = 35 marks.