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-   -   Average speed (https://www.askmehelpdesk.com/showthread.php?t=450839)

  • Feb 23, 2010, 04:18 PM
    apsa ku fan
    Average speed
    If a speedometer currently reads 62 mph, but only 54 miles have been covered during the last hour, what is the average speed? Is it 62 mph, 54 mph, or the average of those two. I can come up with reasonable ways for any of them to be the answer, but right now I'm leaning towards 54 mph, because if they have been traveling for an hour and you have gone 54 miles, that would be 54 mph right? I just don't get how the 62 mph fits in.
  • Feb 23, 2010, 07:02 PM
    Scleros

    What is a reasonable way for 62 or the average of 62 and 54 to be the correct answer?
  • Feb 23, 2010, 08:04 PM
    FlyYakker

    Do you know how an average is calculated? Knowing that will let you decide on the best answer.
  • Feb 24, 2010, 08:04 AM
    Unknown008

    In case you are still confused, your answer is good. If you want to know how the speedometer can read 62 mph, just post back. It's an easy to understand concept.
  • Feb 24, 2010, 08:39 AM
    apsa ku fan
    Well I thought they were reasonable at first. Most people thought it would be the average, 58. Now I think it was just a trick question. 54 mph is the obvious answer. Thank you.
  • Feb 24, 2010, 09:25 AM
    Unknown008

    Remember average speed is Total Distance divided by total time.

    Now if you got an accelerating body, you go from 0 mph to 50 mph quickly, without the need to cover 50 miles.
  • Feb 25, 2010, 08:13 AM
    apsa ku fan
    It was a question for homework, and I just wanted to see other people's opinion to see if they agreed. I actually got the question wrong and the teacher said it was 58, which is the average. I still don't see how he counted it wrong.
  • Feb 25, 2010, 03:45 PM
    FlyYakker

    Whoa! Average of what? 54 and 62? Gimme a break! What if the final speed had been, say, 26 MPH? The average speed would have been 40 MPH if the teacher's method is used. How could he say 40 is the average? You still went 54 miles at an average of 40 MPH?


    Regarding your original post where you didn't see where 62 fits in.. . in this case it just happens to be an endpoint number... perhaps interesting, but not relevant per se. HOWEVER, always be aware that in these written type problems you often get more information than you need (as in real life) and you have to separate out what is usable information and what is not. The folks that wrote the problem are trying to teach you that it's not just about the numbers, but also about understanding what is relevant and what is not.
  • Feb 25, 2010, 07:34 PM
    apsa ku fan
    You I thought they were just putting the 62 mph in there to make it a type of trick question. Even though the teacher counted it wrong, I still believe the answer shoul dbe 54 mph, and that the teachers method is flawed. Im going to ask him to explain it again, because I still don't see his reasoning. The way the question is worded though is very vague, but the way it is worded the only answer should be 54 mph.

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