# 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.

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

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.

Silver Answered on December 5, 2017.