Sunday, May 8, 2016

algebra precalculus - Work Problem that deals with Number of Men, Days, Leaving



A project can be done by 70 men in 100 days. There were 80 men at the start of the project but after 50 days, 20 of them had to be transferred to another project. How long will it take the remaining workforce to complete the job?



The correct answer is 50.



Any hints on how to go about this? I have encountered work problems before with the general formula
1A+1B+=1T.




There's also problems with time involved:



tA(1A+1B)+tB(1C+1D)=1.



This problem incorporates people leaving, remaining days. But I am not sure how to combine them concepts.


Answer



Think about the required amount of work in man-days. The project requires 70100=7000 man-days of total work. After 8050=4000 man-days of work, there are 70004000=3000 man-days of work remaining, and there are 60 remaining workers, so the project will take another 3000/60=50 days.


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