A. 1/12

B. 1/6

C. 1/4

D. 1/3

A can run 1 km in 3 min. 10 sec. and B cover the same distance in 3 min. 20 sec. By what distance can A beat B?

A 270-metre-long train running at the speed of 120 kmph crosses another train running in opposite direcion a the speed of 80 kmph in 9 secs. What is the length of the other train?

In a river flowing at 2 km/hr, a boat travels 32 km upstream and then returns downstream to the starting point. If speed in still water be 6 km/hr, find the total journey time.

If a man cycles at 10 km/hr, then he arrives at a certain place at 1 p.m. If he cycles at 15 km/hr, he will arrive at the same place at 11 a.m. At what speed must he cycle to get there at noon?

There are 5 duplicating machines in an office. The fastest of the machines makes P copies in 10 hours and the slowest of the machines makes P copies in 11 hours. If each machine makes P copies then the average time per machine cannot be