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    Question

    A boat can travel 16 km more in downstream than that in

    upstream, in 8 hours while the difference between the time taken by the same boat to travel 170 km and 120 km, in still water, is 5 hours. Find the approximate time taken by the boat to travel 300 km in downstream and 150 km in upstream.
    A 60 hours Correct Answer Incorrect Answer
    B 32 hours Correct Answer Incorrect Answer
    C 50 hours Correct Answer Incorrect Answer
    D 44 hours Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of boat in still water and speed of stream be 'x' km/hr and 'y' km/hr, respectively. According to question; (170/x) - (120/x) = 5 Or, (50/x) = 5 So, x = 10 Now, 8 x (10 + y) = 8 x (10 - y) + 16 Or, 80 + 8y = 80 - 8y + 16 Or, 16y = 16 So, y = 1 So, downstream speed of the boat = (10 + 1) = 11 km/hr And, upstream speed of the boat = (10 - 1) = 9 km/hr Required time taken = (300/11) + (150/9) ~ (27 + 17) ~ 44 hours

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