Question 16300
I've never solved a problem like this before, but let me take a shot at it.  Maybe you would like to repost the question, and get a second opinion from someone else.


The way I look at it, if the job can be done by 11 workers in 15 days, then it will take a total of 165 worker-days to get the job done.  In other words if one person is working alone it will take a total of 165 days to do it.  If 5 people work on it, it will be done in 165/5 = 33 days.


So, if 5 worker start the job and work for 5 days, they will get 25 worker-days worth of the job done, leaving 140 worker-days left after the first 5 days are accomplished.  Now, 4 more workers come in to reinforce the job, so there are 9 workers working from this point on.  So, divide 140 worker-days by 9 workers which gives you 15.55 days.  In other words they will finish on the 16th day plus the first 5 days of work.  I would say that they finish on the 21st day from the day they started.


R^2 at SCC