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

    Question

    A boat traveled a distance of 135 km from point 'A' to

    point 'B' and then returned to point 'A,' completing the entire journey in 54 hours. The boat's speed in still water is 1.5 times the speed of the stream. Determine the time required for the boat to cover a distance of 180 km in still water.
    A 9 hours Correct Answer Incorrect Answer
    B 18 hours Correct Answer Incorrect Answer
    C 6 hours Correct Answer Incorrect Answer
    D 20 hours Correct Answer Incorrect Answer
    E 15 hours Correct Answer Incorrect Answer

    Solution

    Let the speed of stream be '2x' km/hr. So, speed of boat in still water = 1.5 X 2x = '3x' km/hr So, upstream speed of the boat = 3x - 2x = 'x' km/hr And downstream speed of the boat = 3x + 2x = '5x' km/hr ATQ, (135/5x) + (135/x) = 54 Or, (27/x) + (135/x) = 54 Or, (162/x) = 54 So, 'x' = (162/54) = 3 Speed of boat in still water = '3x' = 3 X 3 = 9 km/hr Therefore, required time = (180/9) = 20 hours

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