Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

jdlandreth

  • 3 years ago

you, in your new red Porsche, decide to make a 160km trip to Carolina Beach, traveling at 80km?hr. Your make a return trip at a rate of 48km?hr. What was your average speed for the entire trip?

  • This Question is Closed
  1. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    figure out the total time, and the total distance divide the total distance by the total time

  2. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok it was easy but i got it wrong total distance is \(2\times 160=320\)

  3. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    time going in your new red porche is \(\frac{160}{80}=2\)

  4. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how about the time returning?

  5. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ugh i don't know cause it comes out as a decimal?

  6. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    much easier (believe it or not) if you leave it as a fraction

  7. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    in other words, take \(\frac{160}{48}\) and instead of writing it as a repeating decimal, reduce it to \(\frac{10}{3}\)

  8. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so far so good?

  9. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay so? then do i leave the other as 2? or 160/2?

  10. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no use 2

  11. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    now the next job is to total up the time, in other words compute \[2+\frac{10}{3}\] leave it as a fraction

  12. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay then what?

  13. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    16/3

  14. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    right and now speed is distance divided by rate

  15. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so your final job is \[320\div \frac{16}{3}\]

  16. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So the average is 60?

  17. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that is what i get too

  18. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    kay good. Thank you!!

  19. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    notice two things 1) the average speed is not the "average of the speeds" and 2) the 160 is a red herring if you really want to impress your math teacher, show that it works no matter how far you drive

  20. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you could drive 160 miles or 100 miles or 3,000 miles or \(m\) miles, the average will still be 60

  21. jdlandreth
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Okay Thank you soo much. =)

  22. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yw

  23. anonymous
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    try it with \(m\) you get \[\frac{2m}{\frac{m}{80}+\frac{m}{48}}=60\] after some algebra

  24. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy