Question

    If a man rows 8km downstream in 6 hours and 4km upstream in 4 hours, then how long will it take him to cover 14km in still water?

    A 8 hours Correct Answer Incorrect Answer
    B 12 hours Correct Answer Incorrect Answer
    C 10 hours Correct Answer Incorrect Answer
    D 6 hours Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Distance in downstream = 8km Time taken = 6 hours Rate of downstream (a) = distance/time  =  4/3 km/hr Distance covered in upstream = 4km Time taken = 4 hours Rate of upstream (b) = distance/time  =   1km/hr Speed in still water = 1/2(a+b) = 1/2(4/3+1)  = 7/6 km/hr  Time taken to cover (14km) in still water = distance/time = 14/(7/6) = 12 hours

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