Question

    Determine the speed of a Ship in calm water, given that the Ship's speed downstream is 20% greater than its speed in still water. If the Ship can cover 48 km both upstream and downstream in a total of 5 hours, what is the speed of the Ship in still water?

    A 30 km/hr Correct Answer Incorrect Answer
    B 20 km/hr Correct Answer Incorrect Answer
    C 50 km/hr Correct Answer Incorrect Answer
    D 45 km/hr Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ, Let speed of Ship in still water is ‘5a’ km/h Speed of Ship in downstream = 1.20 × 5a = 6a Speed of stream = 6a – 5a = a km/h Speed of Ship in upstream = 5a – a = 4a km/h So, (48/6a) + (48/4a) = 5 Or, (8/a) + (12/a) = 5 Or, a = (8 + 12)/5 = 4 Speed of Ship in still water = 5 × 4 = 20 km/hr

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