A swimmer registers 12 km upstream and 24 km downstream, taking 3 hours for each leg of the trials. Find the speed of the current stream. MCQ with Answer and Explanation
A person row a boat 12 km downstream in 1 hour. If the river current flows at 3 km/h, find the time taken by the boat to row the same distance upstream.
Explanation:
Downstream speed = 12 / 1 = 12 km/h. Baseline boat speed in still water = Downstream speed - Current speed = 12 - 3 = 9 km/h. Upstream speed = Still water speed - Current speed = 9 - 3 = 6 km/h. Time taken upstream = Distance / Upstream speed = 12 / 6 = 2 hours.
A passenger train 100 meters long clears a line worker tracking on the ballast track in 5 seconds flat when both move along the identical direction. If the line worker walks at 8 km/h, find the train speed.
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