SOLUTION: It takes Paul 4 hours to do a job. It takes Peter 2 hours to do that same job. How many such jobs could they do together in 4 hours?

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Question 614391: It takes Paul 4 hours to do a job. It takes Peter 2 hours to do that same job. How many such jobs could they do together in 4 hours?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
It takes Paul 4 hours to do a job.
It takes Peter 2 hours to do that same job.
How many such jobs could they do together in 4 hours?
:
Let t = time when both of them to do one job
Let one completed job = 1
:
t%2F4 + t%2F2 = 1
multiply by 4
t + 2t = 4
3t = 4
t = 4%2F3 hr for both of them to do one job
:
Find how many jobs they could do in 4 hrs
4 divided by 4%2F3
invert the dividing fraction and multiply
4 * 3%2F4 = 3 jobs in 4 hrs