Unformatted text preview: s very similar to the formula we used above. © 2007 Paul Dawkins 76 http://tutorial.math.lamar.edu/terms.aspx College Algebra Example 8 An office has two envelope stuffing machines. Machine A can stuff a batch of
envelopes in 5 hours, while Machine B can stuff a batch of envelopes in 3 hours. How long
would it take the two machines working together to stuff a batch of envelopes?
Solution
Let t be the time that it takes both machines, working together, to stuff a batch of envelopes. The
word equation for this problem is, æ Portion of job ö æ Portion of job ö
ç
÷+ç
÷ = 1 Job
è done by Machine A ø è done by Machine B ø
æ Work Rate öæ Time Spent ö æ Work Rate öæ Time Spent ö
ç
÷ç
÷+ç
÷ç
÷ =1
è of Machine A øè Working ø è of Machine B øè Working ø
We know that the time spent working is t however we don’t know the work rate of each machine.
To get these we’ll need to use the initial information given about how long it takes each machine
to do the job individually. We can use the following...
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 Spring '12
 MrVinh
 ........., Paul Dawkins

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