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

    Question

    A boat takes 7 hours to move 63 km downstream and 30 km

    upstream. The boat takes 6 hours to move 28 km downstream and 48 km upstream. How much time will it take to move 35 km downstream and 27 km upstream?
    A 4 hours 45 minutes Correct Answer Incorrect Answer
    B 4 hours 50 minutes Correct Answer Incorrect Answer
    C 5 hours Correct Answer Incorrect Answer
    D 5 hours 20 minutes Correct Answer Incorrect Answer

    Solution

    Let the Speed of the boat in still water B And Speed of Stream =S Let downstream speed be (B+ S) and upstream speed be (B - S) Now, By multiplying 8 with eq (i) and 5 with eq (ii) we get Subtracting eq (iv) from eq (iii) we get, B+S =364/26 B+S =14 Putting the of (u + v) in eq (ii) we get, B-S =12. Now, To move 35 km downstream and 27 km upstream time = 35/14 + 27/12 =2.5+ 2.25        =4.75 =4 hours 0.75×60 minutes. =4 hours 45 minutes.

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