Cumulative frequency

Build the cumulative table for the frequencies 2, 5, 9, 4 in the classes 0–, 10–, 20–, 30–40.

The cumulative values for less than 5, 10, 15, 20 are 4, 11, 25, 30 (0 at 0). Find the frequencies.

Give the points to plot for the cumulative table 0, 4, 11, 25, 30 at the limits 0, 5, 10, 15, 20.

From the cycling curve, how many pupils took at least 20 minutes, and what percent is that?

From the cycling curve, estimate how many pupils took less than 15 minutes.