A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Working together, 7 identical pumps can empty a pool in 6 hours. How many hours will it take 4 pumps to empty the same pool?

  • This Question is Closed
  1. AkashdeepDeb
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    7 identical pumps => 6 hours 4 identical pumps => ? hours Statement: More pumps, less time. Inversely proportional. Solution: No. of pumps in 1st case * time taken in 1st case = no. of pumps in second case * time taken in 2nd case. Think of it like this: 42 identical pumps would be needed to do it in 1 hour.

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

    I dont understand why it's 7*6 @AkashdeepDeb

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

    how do i even know what 7*6 calculates

  4. AkashdeepDeb
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    If I travel at 60 km/hr in a car, I can cover a distance x in 1 hour. If I travel at 120 km/hr can you guess how much time it'll take to cover the same distance?

  5. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    not sure

  6. AkashdeepDeb
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    7*6 calculates the volume of the pool, per se. Basically, it remains constant, because, obviously, the pool's volume won't change.

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

    hmmmmm.... trying to process this in my head

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

    60*x / 120

  9. AkashdeepDeb
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Ohkay. Let me use a similar example. I want to right a book with a fixed number of words. I can right 30 words per minute for 10 minutes. If I can increase my speed to 60 words per minute, how much time will it take me to write the book? See, what's happening here. I STILL have to write the same number of words! If I can finish writing a book by writing at 30 words per minute for 10 minutes, I am writing 30 * 10 words = 300 words. Now, if I write a 60 words per minute, I still have to write 300 words. That would take me 300/60 = 5 minutes to write.

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

    can i do proportions with this?

  11. AkashdeepDeb
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    It's just like the basic equation: \(Time * Speed = Distance\) The Distance, always remains constant. In your case, the volume of pool is constant.

  12. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok got it i think

  13. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did u want some help with this, you bumped it up?

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

    do u have a different interpretation?

  15. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    well there was a great trick suggested already

  16. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    let h be hours 7*6 = 4*h, is a nice simplification, but the logic behind it, u have to think about it a little

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

    why is it 7*6

  18. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    it doesnt have to it, this relation just exists between the 7 and 4 and the number of hours

  19. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Here is another way to approach the problem, okay lets just say there is some work W, that needs to be done

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

    yes

  21. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    7 pumps take 6 hours to complete this work,, which means each pump worked for 6 hours

  22. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    7 of these pumps worked for 6 hours in total

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

    yes

  24. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay so lets say it was just 1 pump, its pretty logical to say this 1 pump has to work 7 times more hours right

  25. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea

  26. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay so

  27. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    now when its 4 pumps, that means we have to work 7/4 times more xD

  28. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea

  29. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so 7/4 * 6 is our hours,

  30. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    hmmmm i see

  31. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so it's proportions?

  32. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    here is another way that 7*6 = 4*h relationship comes up

  33. dan815
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i forgot what i was about to say xD

  34. Baseballguy101
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i always solve problems like this another way. if you have 7 pumps that empty a pool in 6 hours you can divide the amount of pumps by the time. so 7/6 then times it by the amount of pumps you're using now. so I would use the equation (7/6)*4

  35. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    lol

  36. Baseballguy101
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    does that make sense to you?

  37. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    kinda...

  38. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay i think i got it... thanks guys

  39. Baseballguy101
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    no problem there are many ways to solve a problem just use the easiest for you!

  40. 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

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.