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

    Question

    A boat travels from point 'T' to point 'S' downstream

    and returns upstream in a total of 32 hours. The speed of the boat in upstream is three times the speed of the stream. The distance between 'S' and 'T' is 240 km. Based on this information, calculate the time it would take for the boat to cover 320 km in still water.
    A 36 hours Correct Answer Incorrect Answer
    B 18 hours Correct Answer Incorrect Answer
    C 16 hours Correct Answer Incorrect Answer
    D 20 hours Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the speed of the stream be 'x' km/hr Or, speed of boat in upstream = '3x' km/hr Or, speed of boat in still water = x + 3x = 4x km/hr Or, downstream speed of boat = 4x + x = 5x km/hr ATQ, (240/5x) + (240/3x) = 32 Or, (48/x) + (80/x) = 32 Or, (128/x) = 32 So, 'x' = 4 Speed of boat in still water = 4 X 4 = 16 km/hr Therefore, required time = (320/16) = 20 hours

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