Question
A man rows a boat 90 kms in 4 hours downstream and
returns upstream in 12 hours. The speed of the stream (in km per hour) is:Solution
Rate downstream = 90/4 = 22.5 km/hr Rate upstream = 90/12 = 7.5 km/hr Now, speed of the stream = (rate downstream – rate upstream)/2 ⇒ (22.5 – 7.5)/2 = 7.5 km/hr
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