Question
A boat takes 15 hours to travel 150 km upstream. When
its speed is doubled, it covers 150 km downstream in 3 hours. Find the speed of the stream.Solution
ATQ,
Upstream speed of the boat = 150 ÷ 15 = 10 km/h Let the original speed of the boat in still water be 'x' km/h and speed of the stream be 'y' km/h. So, x - y = 10 ...... (I) Downstream speed of the boat when doubled = 150 ÷ 3 = 50 So, 2x + y = 50 ......... (II) On adding (I) and (II): 3x = 60 x = 20 So, 20 - y = 10 y = 10 Speed of the stream = 10 km/h
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