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:
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Answer:
Explanation:
=> Suppose,
the Speed of boat = x km/hr
Speed of current = y km/hr
Thus, Upstream speed = x - y
Downstream speed = x + y
=> Accoring to the question,
A boat sails 15 km of a river towards upstream in 5 hours.
x - y = 15/5 [speed = distance / time]
x - y = 3
=> Time needed by boat to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water:
Thus, x : y = 1 : 4
x + y = 15 / time
1 + 4 = 15 / time
5 = 15 / time
time = 15/5 = 3 hr
Thus, time needed by boat to cover the same distance downstream is 3 hr.
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