New FLASH SALE Dhamaka - Flat 60% Off on All Courses

    Question

    The speed of current is 8 km/h. What will be the

    respective downstream speed and upstream speed of a boy rowing a boat, if one fifth 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 20 km/h, 4 km/hr Correct Answer Incorrect Answer
    D 30 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 = 8 km/h Downstream speed = (X + 8) km/h Upstream speed = (X – 8) km/h Let time be ‘t’ hours. ⇒ [(X + 8) t]/5 = (X – 8) t ⇒ X + 8 = 5X – 40 ⇒ X = 12 km/h Downstream speed = 12 + 8 = 20 km/h Upstream speed = 12 – 8 = 4 km/h

    Practice Next