Draw histograms for the following frequency distributions :

Class interval	Frequency
30 - 39	24
40 - 49	16
50 - 59	09
60 - 69	15
70 - 79	20

The above distribution is discontinuous, converting into continuous distribution, we get :

Adjustment factor = (Lower limit of one class - Upper limit of previous class) / 2

= $\dfrac{40 - 39}{2} = \dfrac{1}{2}$

= 0.5

Subtract the adjustment factor (0.5) from all the lower limits and add the adjustment factor (0.5) to all the upper limits.

Steps of construction of histogram :

1. Since, the scale on x-axis starts at 29.5, a break (kink) is shown near the origin on x-axis to indicate that the graph is drawn to scale beginning at 29.5.

2. Take 2 cm along x-axis = 10 units.

3. Take 2 cm along y-axis = 5 units.

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

The required histogram is shown in the below figure: