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    Question

    A boat can travel 12 km more in downstream than that in

    upstream, in 3 hours while the difference between the time taken by the same boat to travel 180 km and 120 km, in still water, is 4 hours. Find the approximate time taken by the boat to travel 267 km in downstream and 183 km in upstream.
    A 20 hours Correct Answer Incorrect Answer
    B 40 hours Correct Answer Incorrect Answer
    C 30 hours Correct Answer Incorrect Answer
    D 10 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; (180/x) - (120/x) = 4 Or, (60/x) = 4 So, x = 15 Now, 3 x (15 + y) = 3 x (15 - y) + 12 Or, 45 + 3y = 45 - 3y + 12 Or,  6y = 12 So, y = 2 So, downstream speed of the boat = (15 + 2) = 17 km/hr And, upstream speed of the boat = (15 - 2) = 13 km/hr Required time taken = (267/17) + (183/13) ~ (16 + 14) ~ 30 hours

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