The heights (in cm) of 15 saplings are grouped as follows:
Class interval: 50–60 | 60–70 | 70–80 | 80–90
Frequency: 2 | 4 | 5 | 4
(i) Prepare the ‘less than’ cumulative frequency column.
(ii) Write the coordinates of the points you would plot for each class while constructing the ‘less than’ ogive.