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

    Question

    A car covers the first 40 km of a journey at 60 km/h and

    the next 60 km at 90 km/h. What is the average speed for the entire journey?
    A 72 km/h Correct Answer Incorrect Answer
    B 75 km/h Correct Answer Incorrect Answer
    C 80 km/h Correct Answer Incorrect Answer
    D 85 km/h Correct Answer Incorrect Answer

    Solution

    Time taken for first 40 km = Distance / Speed = 40 / 60 = 2/3 hours. Time taken for next 60 km = 60 / 90 = 2/3 hours. Total distance = 40 + 60 = 100 km. Total time = 2/3 + 2/3 = 4/3 hours. Average speed = Total distance / Total time = 100 / (4/3) = 75 km/h. Answer: b) 75 km/h.

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