Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Workers, days, product.

  1. Oct 19, 2011 #1
    1. The problem statement, all variables and given/known data

    It takes 2 workers 3 days to make 10 units. How many workers would it take to make 30 units in 2 days?

    2. Relevant equations

    I'm not sure of what equations to use.

    3. The attempt at a solution

    I've tried techniques such as laying out the equations and using substitution, but I'm really not sure how to work this particular problem.

    I don't know if this is posted on another thread, if so, I would appreciate a link very much.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 19, 2011 #2

    Mark44

    Staff: Mentor

    Show us what you've tried, even if it's wrong.

    Look at this in terms of what a single worker can do in one day.
     
  4. Oct 19, 2011 #3
    ok. well pretty much I just set some equations up such as,

    d*w=p
    2w*3d=10p

    But I realized this is not the right approach.

    Just now in the writing of this post, I think I may have figured out how to do it. I made into a constant(k) type problem.

    pretty much I put that the product varies directly with the amount of workers multiplied by the time in days.

    p=kwd

    I then just solved for constant, k, using the equation which gives me all the values of the variables. I got k = 5/3 and my answer for the problem was 9, which was a choice among 5, 6, 9, 18.

    I do believe this the the correct method for this type of problem, but of course, please tell me if it is not. thanks.
     
  5. Oct 19, 2011 #4

    Mark44

    Staff: Mentor

    I agree with your answer. Here is my reasoning.

    One worker can make 5 units in 3 days, so each worker can make 5/3 unit per day.

    So in 2 days, one worker can make 2*5/3 = 10/3 units. To make 30 units, you need 30/(10/3) = 30 * 3/10 = 9 workers.
     
  6. Oct 19, 2011 #5
    that makes sense, thanks.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook