Question

    Two boats X and Y start towards each other from two

    places, 168 km apart. Speed of the boat X and Y in still water are 9 km/hr and 12 km/hr respectively. If X proceeds down and Y up the stream, they will meet after.
    A 4 hours Correct Answer Incorrect Answer
    B 5 hours Correct Answer Incorrect Answer
    C 6 hours Correct Answer Incorrect Answer
    D 7 hours Correct Answer Incorrect Answer
    E 8 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of the stream be x km/hr and both the boats meet after t hours According to the question, ⇒ (9 + x) t + (12 – x) t = 168 ⇒ 9t + 12t = 168 ⇒ 21t = 168 ⇒ t = 168/21 = 8 hours

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