Question

Boat moves upstream in 6 hrs and covers the same distance downstream in 5 hrs. then speed of a raft floating?

Answer 1

Let the speed of boat(raft) = X km/hr
Speed of stream = Y km/hr

Let the distance be 'D' Km
Upstream Speed = X - Y
Downstream speed = X + Y
Upstream time = 6 = D/X-Y....(i)
Downstream time = 5 = D/X+Y...(ii)
(i) divided by (ii)
6/5 = X+Y/X-Y
6X - 6Y = 5X + 5Y
X = 11 Y
Hence speed of boat in still water = 11* speed of stream(water)
Speed of stream(water) = Speed of boat/11
[Since distance is not given, this is the only method i could figure out.]
Hope it helps.