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    Question

    Speed of a boat in still water is 6 times more than the

    speed of stream. If boat covers 144 km in downstream in 9 hours, then find the time taken by the boat to cover 120 km in upstream.
    A 12 hours Correct Answer Incorrect Answer
    B 10 hours Correct Answer Incorrect Answer
    C 8 hours Correct Answer Incorrect Answer
    D 9 hours Correct Answer Incorrect Answer
    E 7 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of stream be ‘x’ km/hr. So, speed of boat in still water = 7 × x = 7x km/hr Downstream speed of boat = 7x + x = 8x km/hr According to question; 8x = 144/9 = 16 Or, x = 2 Upstream speed of the boat = 7x – x = 6x = 6 × 2 = 12 km/hr Required time taken = 120/12 = 10 hours

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