Two trains starting at the same time from two stations 200 km apart and going in opposite directions cross each other at a distance of 110 km from one of the stations. What is the ratio of their speeds?
A) 9 : 20
B) 11 : 9
C) 11 : 20
D) None of these
Answer: B) 11 : 9
In the same time, they cover 110 km and 90 km respectively.
Therefore, Ratio of their speeds = 110 : 90 = 11 : 9
Mark had to travel 220 km in 4.5 hours, using a train that travels at the speed of 60 km/h or a bus that travels at the speed of 40 km/h, or any combination of the two modes of transport. For how long did he travel by bus?