Explanation:

 A truck covers a distance of 550 metres in 1 minute whereas a bus coveres a distance of 33 kms in 45 minutes. The ratio of their speeds is ?

Distance cover by truck=550/1000 km  and time taken=1/60 hr

speed of truck=(550/1000)  /(1/60)=33km/hr

Distance cover by bus=33 km  and time taken=45/60 hr

speed of Bus=33  /(45/60)=44km/hr

Ratio of speed        truck   :    Bus

                               33       :     44

                                 3        :   4