Question

    A boat running downstream covers a distance of 18 km in

    2 hrs while it covers the same distance upstream in 3 hrs. Then speed of the boat in still water is
    A 5 km/hr Correct Answer Incorrect Answer
    B 3 km/hr Correct Answer Incorrect Answer
    C 15 km/hr Correct Answer Incorrect Answer
    D 7.5 km/hr Correct Answer Incorrect Answer
    E 18 km/hr Correct Answer Incorrect Answer

    Solution

    Let the speed of boat in still water be a km/hr and that of stream be b km/hr. Therefore, 18/(a + b)= 2 ⇒ a + b = 9 ………..(i) 18/(a – b)= 3 ⇒ a + b = 6 ………..(ii) On adding, eq (i) and (ii) ⇒ 2a = 15 km/hr ⇒ a = 7.5 km/hr

    Practice Next