Question 355008: it takes 7 people 8.5 hours to complete a job how long would it take 4 people? Found 2 solutions by robertb, ptaylor:Answer by robertb(5830) (Show Source):
You can put this solution on YOUR website! The rate of contribution of a person per hour is .
If 4 people are working, then let
x = #number of hours to finish job. Then , hours.
You can put this solution on YOUR website! Let x=amount of time it takes 4 people to complete the job. Then 4 people work at the rate of 1/x of the job per hour.
If it it takes 7 people 8.5 hrs to complete the job, then the job requires 7*(8.5) or 59.5 people-hours to complete. In other words, one person can complete the job in 59.5 hours. So one person works at the rate of 1/59.5 of the job per hour; 4 people work at the rate of 4/59.5 of the job per hour. Soooo our equation to solve is:
1/x=4/59.5
1/x=4/59.5
4x=59.5 hrs
x=14.875 hrs
CK
1 person needs 59.5 hrs to complete the job
2 people need (59.5)/2 =29.75 hrs to complete the job
4 people need(59.5)/4=14.875 hrs to complete the job
7 people need (59.5)/7=8.5 hrs to complete the job
Hope this helps
