Sam covers a total distance of 80km while travelling from a certain point X to a certain point Y and come back again to the start point X. He covers the first 40 km distance from point X to point Y at a speed of 25 km/hr. While travelling back to the point X from point Y, Sam drives his vehicle at a speed of 15 km/hr. Calculate the average speed of Sam for the entire journey.

I cannot solve this problem Please help.

Sam covers a total distance of 80km while travelling from a certain point X to a certain point Y and come back again to the start point X. He covers the first 40 km distance from point X to point Y at a speed of 25 km/hr. While travelling back to the point X from point Y, Sam drives his vehicle at a speed of 15 km/hr. Calculate the average speed of Sam for the entire journey.

Default Asked on December 5, 2017 in Mathematic.
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1 Answer(s)

    Thank you very much for your question. I’m very glad to know that you have come to a question-answer website to solve your problem. That means, you have a strong will to learn this math. I really appreciate it. Thank you again.

    Your question is – Sam covers a total distance of 80km while travelling from a certain point X to a certain point Y and come back again to the start point X. He covers the first 40 km distance from point X to point Y at a speed of 25 km/hr. While travelling back to the point X from point Y, Sam drives his vehicle at a speed of 15 km/hr. Calculate the average speed of Sam for the entire journey.

    I have solved this problem thus, you can read my Explanation for your better understanding:

    We know the standard formula for speed, time and distance as, distance = speed * time.
    Using this formula we can easily find out the correct answer to the above question.

    According to the question,
    Total distance covered by Sam = 80 km …..i
    Speed of Sam while travelling from point X to point Y = 25 km/hr …..ii
    ∴ Time taken by Sam to go from point X to point Y = 40/25 = 1.6 hours …..iii
    Speed of Sam while travelling back from point Y to point X = 15 km/hr …..iv
    ∴ Time taken by Sam to go from point Y to point X = 40/15 = 2.66 hours …..v
    ∴ The total time to cover the total distance of 80 km = 1.6 + 2.66 = 4.26 hours …..vi
    ∴ Average speed for the entire round trip = 80/4.26 = 18.77 km/hr

    Thanks.

    Brong Answered on December 5, 2017.
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