Question (3/42)
A motorboat, whose speed is 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. What is speed of stream ?(A)  4 km/hr
(B)  5 km/hr
(C)  6 km/hr
(D)  7 km/hr
Question (4/42)
Ship covers a certain distance downstream in 1 hour, while it comes back in `1 1/2` hour. If the speed of the stream is 3 km/hr, then what is speed of ship in still water ?(A)  12 km/hr
(B)  13 km/hr
(C)  14 km/hr
(D)  15 km/hr