Question
A boat can travel 45 km downstream in 50 min. The ratio
of the speed of the boat in still water to the speed of the stream is 5: 4. How much time will the boat take to cover 22 km upstream?Solution
Speed of downstream = D/T = 45 × (60/50) = 54 km/hr The ratio of the speed of the boat in still water to the speed of the stream = 5: 4 (5x, 4x) => 9x = 54 => x = 6 Speed of upstream = 5x – 4x = x = 6 km/hr Distance = 22 km Time = D/S = 22/6 = 3(2/3) hr = 3 hour 40 min
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