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    Question

    Speed of a boat in still water to speed of boat in

    upstream is 13:10. If the boat can travel 320 km in downstream in 5 hours, then find the time taken by the boat to cover 13 km in still water.
    A 30 minutes Correct Answer Incorrect Answer
    B 20 minutes Correct Answer Incorrect Answer
    C 15 minutes Correct Answer Incorrect Answer
    D 18 minutes Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let speed of boat in still water and speed of boat in upstream be ‘13x’ km/h and ‘10x’ km/h, respectively. Speed of stream = 13x – 10x = 3x km/h Speed of boat in downstream = 13x + 3x = 16x km/h So, 16x = 320/5 = 64 Or, x = 4 Speed of boat in still water = 13 × 4 = 52 km/h Desired time = 13/52 = 15 minutes

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