A boat sails 15 km of a river towards upstream in 5 hours.
A boat sails 15 km of a river towards upstream in 5 hours. How long will it take to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water:
Answer/Solution
3h
Steps/Work
Explanation:
Upstream speed = B-S
Downstream speed = B + s
B - S = 15/5 = 3 km/h
Again B = 4S
Therefore B - S = 3 = 3S
=> S = 1 and B = 4 km/h
Therefore B + S = 5km/h
Therefore, Time during downstream = 15/5 = 3h
Answer: B
Upstream speed = B-S
Downstream speed = B + s
B - S = 15/5 = 3 km/h
Again B = 4S
Therefore B - S = 3 = 3S
=> S = 1 and B = 4 km/h
Therefore B + S = 5km/h
Therefore, Time during downstream = 15/5 = 3h
Answer: B