Question

Draw a histogram and hence estimate the mode for the following frequency distribution: 

Class	0-5	5-10	10-15	15-20	20-25	25-30
Freq	0	7	18	10	8	5

Answer 1

Histogram is as follows:

In the highest rectangle which represents modal class draw two lines AC and BD intersecting at E. 
From E, draw a perpendicular to x-axis meeting at L.
Value of L is the mode. Hence, mode = 13