A man takes thrice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat (in still water) and the stream is:

 a) 2 : 1
 b) 3 : 1
 c) 3 : 2
 d) 5 : 3

2 : 1. Solution Let speed upstream = k Then, speed downstream = 3k Speed in still water = (3k + k)/2 = 2k Speed of the stream = (3k - k)/2 = k Speed in still water : Speed of the stream = 2k : k = 2:1