Question
A boatman takes 9 hours to cover 64 km downstream and 60
km upstream. If the ratio of his speed downstream to his speed upstream is 4:3, what is the speed of the stream?Solution
Let the downstream speed and upstream speed be ‘4x’ km/h and ‘3x’ km/h, respectively. According to question, 64/4x + 60/3x = 9 16/x + 20/x = 9 36/x = 9, x = 4 So, the downstream speed and upstream speed is 16 km/h and 12 km/h, respectively. Speed of stream = (16 – 12)/2 = 2 km/h
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