Question
The speed of a boat in still water is 5.5 times the
speed of the stream. If the difference between the upstream and downstream speed of the boats is 25 km/hr, then find the time taken by the boat to travel 225 km in upstream.Solution
Let the speed of the stream be ‘x’ km/hr Therefore, speed of the boat in still water = ‘5.5x’ km/hr Upstream speed of the boat = 5.5x – x = ‘4.5x’ km/hr Downstream speed of the boat = x + 5.5x = ‘6.5x’ km/hr According to the question, 6.5x – 4.5x = 25 => 2x = 25 => x = 12.5 Therefore, upstream speed of the boat = 4.5x = 56.25 km/hr Required time taken = 225/56.25 = 4 hours
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