SOLUTION: Dan can do the job in 30 hours, Ellen can do it in 40 hours, and Francis can do it in 60 hours. How long would it take them if they work together? (use only one variable)(thanks in
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-> SOLUTION: Dan can do the job in 30 hours, Ellen can do it in 40 hours, and Francis can do it in 60 hours. How long would it take them if they work together? (use only one variable)(thanks in
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Question 1132152: Dan can do the job in 30 hours, Ellen can do it in 40 hours, and Francis can do it in 60 hours. How long would it take them if they work together? (use only one variable)(thanks in advance) Found 2 solutions by Alan3354, ikleyn:Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! Dan can do the job in 30 hours, Ellen can do it in 40 hours, and Francis can do it in 60 hours. How long would it take them if they work together?
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h hours.
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1/h = 1/30 + 1/40 + 1/60
Dan makes of the entire job per hour. It is his rate of work.
Ellen makes of the entire job per hour. It is her rate of work.
Francis makes of the entire job per hour. It is his (or her (?) ) rate of work.
Working together, the tree persons make = = = of the entire job per hour.
It is their COMBINED rate of work, which is the sum of the individual rates.
To solve the problem using one variable, introduce t as the time it takes them to complete the entire job working together.
Then your equation is Time*Rate = the entire job, or
= 1,
which implies
t = = = hours = 13 hours and 20 minutes. ANSWER
