A railway line monitored 15% of its August train journeys to find their departure delay times. The results are shown below. It is given that 24 of these journeys were delayed by less than 2 minutes.

a. How many journeys were monitored?

b. Calculate an estimate of the number of these journeys that were delayed by:

i. 1 to 3 minutes 

ii. 10 to 15 minutes.

c. Show that a total of 2160 journeys were provided in August.

d. Calculate an estimate of the number of August journeys that were delayed by 3 to 7 minutes. State any assumptions that you make in your calculations.

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