SOLUTION: Three workers can complete a job in 3 hours, 5 hours, and 6 hours, respectively. How long will it take the workers to complete the job if they work together?

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Question 32150: Three workers can complete a job in 3 hours, 5 hours, and 6 hours, respectively. How long will it take the workers to complete the job if they work together?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
The key to these kinds of problems is to find the rate (in this case, the hourly rate) at which each worker can accomplish his/her part of the job.
Worker A can do the job in 3 hours, so he/she can do 1/3 of the job in 1 hour.
Worker B can do the job in 5 hours, so he/she can do 1/5 of the job in 1 hour.
Worker C can do the job in 6 hours, so he/she can do 1/6 of the job in 1 hour.
Working together, they can do 1/3 + 1/5 + 1/6 of the job in 1 hour.
1%2F3+%2B+1%2F5+%2B+1%2F6+=+10%2F30+%2B+6%2F30+%2B+5%2F30 = 21%2F30
If they can do21%2F30 of the job in 1 hour, then they can do the complete job in 30%2F21hours.
30%2F21hours = 1 hour 25.7 minutes.