Aptitude day 255

Problems on Boats and Streams:

1. A man can row at 6 kmph in still water. If the velocity of the current is 2 kmph and it takes him 1 hour to row to a place and comes back, how far is the place?

Solution:

                 Speed of the downstream = 5+1 = 6 km/hr.

                 Speed of the upstream = 5-1 = 4 km/hr.

                 Let x be the distance.

                 x/8 + x/4 = 1.

                 By solving the above equation, we get

                 x = 2.7 km.

2. A boat covers a certain distance downstream in 2 hours, while it comes back in 3(1/2) hours. If the speed of the stream be 5 km/hr, what’s the speed of the boat in still water?

Solution:

                  Let the speed of the boat in still water be u.

                  2(u+5) = 7/2[u-5]

                  By solving the above equation, we get

                  u = 5 km/hr.