Draw a histogram for the following data :

Class marks	Frequency
12.5	7
17.5	12
22.5	20
27.5	28
32.5	8
37.5	11

We know that class mark is the mid-point of class. So, frequency distribution table for above data is :

Steps of construction of histogram :

1. Since the scale on x-axis starts at 10, a kink is shown near the origin on x-axis to indicate that the graph is drawn to scale beginning at 10.

2. Take 2 cm along x-axis = 5 units.

3. Take 1 cm along y-axis = 5 units.

4. Construct rectangles corresponding to the above continuous frequency distribution table.

The required histogram is shown in the adjoining figure.