Question
A boat has a speed of 18 km/h in still water, while the
stream flows at 6 km/h. How much time (in hours) will it take the boat to travel 180 km upstream and then 75% of that distance downstream?Solution
Speed of boat in downstream = 18 + 6 = 24 km/h
Speed of boat in upstream = 18 – 6 = 12 km/h
So, desired time = 0.75 × 180/24 + 180/12 = 5.625 + 15 = 20.625 hours
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