on the assumption that the top speed of a train on this line is 60 km per hour, that it takes
3 minutes to reach this speed from rest, and 1 minute to bring the train to a stop, both at a
constant rate; and that at an intermediate station 1 minute must be allowed to set down and
pick up passengers. How long must the timetable allow for the whole journey
(a) for trains which don't stop at Beeburg,
(b) for trains which do stop at Beeburg?