New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The speed of current is 4 km/h. What will be the

    respective downstream speed and upstream speed of a boy rowing a boat, if half of the distance covered going downstream in a certain time is equal to the distance covered going upstream in the same time?
    A 28 km/h, 14 km/hr Correct Answer Incorrect Answer
    B 15 km/h, 5 km/hr Correct Answer Incorrect Answer
    C 16 km/h, 8 km/hr Correct Answer Incorrect Answer
    D 18 km/h, 6 km/hr Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of boy in still water be X km/h. And the speed of current = 4 km/h Downstream speed = (X + 4) km/h Upstream speed = (X – 4) km/h Let time be ‘t’ hours. ⇒ [(X + 4) t]/2 = (X – 4) t ⇒ X + 4 = 2X – 8 ⇒ X = 12 km/h Downstream speed = 12 + 4 = 16 km/h Upstream speed = 12 – 4 = 8 km/h

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