Question

Bus A and Bus B leave the bus depot at 6 pm. Bus A takes 20 minutes to complete its route once and bus B takes 45 minutes to complete its route once. If both buses continue to repeat their route, at what time will they be back at the bus depot together? Assume the buses have no breaks in between routes. Give your answer as a 12-hour clock time

Answer 1

Bus Bs route times will be:

45 mins
90 mins
135 mins
180 mins

Bus As times will be:

20 mins
40 mins
60 mins
...
180 mins.

Therefore 180 mins is the common factor, which is 9pm