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    Question

    Speed of the stream is 15 km/h and speed of boat in

    still water is 24 km/h. A boat takes a total of 38 hours for travelling downstream from Point M to Point N and coming back to point Q which is midway of point M and N. What is the distance between M and N?
    A 560 km Correct Answer Incorrect Answer
    B 352 km Correct Answer Incorrect Answer
    C 432 km Correct Answer Incorrect Answer
    D 468 km Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the distance between M and N = a km Speed of boat in upstream = 24 – 15 = 9 kmph Speed of boat in downstream = 24 + 15 = 39 kmph It takes 38 hours to complete the whole distance, ⇒ a/39 + 1/2 × a/9 = 38 ⇒ a/39 + a/18 = 38 ⇒ 19a/234 = 38 ⇒ a = (38 × 234)/19 ⇒ a = 468 km

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