Question
The speed of a boat in still water is 13 times the speed
of the stream. If the difference between the upstream and downstream speed of the boats is 30 km/hr, then find the time taken by the boat to travel 540 km in upstream.Solution
Let the speed of the stream be ‘x’ km/hr Therefore, speed of the boat in still water = 13x km/hr Upstream speed of the boat = 13x – x = 12x km/hr Downstream speed of the boat = x + 13x = 14x km/hr According to the question, 14x – 12x = 30 => 2x = 30 => x = 15 Therefore, upstream speed of the boat = 12x = 180 km/hr Required time taken = 540/180 = 3 hours
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