SOLUTION: A 3-men crew can do a certain job in 4 hours, while it takes a 4-men crew to do the same job 3 hours. How long will it take to complete the job if two crews work together, and one

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A 3-men crew can do a certain job in 4 hours, while it takes a 4-men crew to do the same job 3 hours. How long will it take to complete the job if two crews work together, and one       Log On


   

Question 531897: A 3-men crew can do a certain job in 4 hours, while it takes a 4-men crew to do the same job 3 hours. How long will it take to complete the job if two crews work together, and one worker from the second crew was 1 hour late? Thank you
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A 3-men crew can do a certain job in 4 hours, while it takes a 4-men crew to do the same job 3 hours.
How long will it take to complete the job if two crews work together, and one worker from the second crew was 1 hour late?
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We know that the job requires 12 man-hours to complete (3*4 or 4*3)
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Let's try and determine how long it would take the 2nd crew to do the job if one guy was 1 hr late (h).
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3 guys work the whole time, one guy works 1 hr less
3h + 1(h-1) = 12
3h + h - 1
4h = 12 + 1
4h = 13
h = 13/4
h = 3.25 hrs to do the job under these conditions
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Now using a standard, shared work equation where the completed job = 1
Crew 1 + crew 2 = completed job
t%2F4 + t%2F3.25 = 1
multiply by 13 to clear the denominators
3.25t + 4t = 13
7.25t = 13
t = 13%2F7.25
t = 1.793 hrs which is 1 hr + .793(60) ~ 1 hr 48 min
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Did this make sense? Let me know if you find out I am wrong on this one. C
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