Looking at the frequency chart, the modal class interval is 15 cm ≤ h < 16 cm as there are 5 pieces of data in this class. Image caption, The time it takes 20 people to run 100 m is recorded.

Proceeding in the same way, we get frequency of all class intervals as below: Marks. Number of students (f i) 0-10 ... The annual rainfall record of a city for 66 days is given in the following table.