SOLUTION: Jane can assemble a computer by herself in 40 minutes. James can do it in 35 mimutes. How long will it take them working together?

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Question 1075948: Jane can assemble a computer by herself in 40 minutes. James can do it in 35 mimutes. How long will it take them working together?
Found 3 solutions by Alan3354, jorel1380, ikleyn:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
Jane can assemble a computer by herself in 40 minutes. James can do it in 35 mimutes. How long will it take them working together?
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40*35/(40+35) minutes
Answer by jorel1380(3719)   (Show Source): You can put this solution on YOUR website!
Jane assembles 1/40th of a computer per minute. James does 1/35th per minute. So, together:
1/40+1/35=1/n
35n+40n=1400
n=1400/75=18.67 minutes working together. ☺☺☺☺
Answer by ikleyn(52786)   (Show Source): You can put this solution on YOUR website!
.
The formal solution is THIS: 

Jane makes  of the job per minute.

Janes makes  of the job per minute.


Working together, they make  =  =  =  of the job per minute.


Hence, they will complete the job in  minutes =  minutes = 18 minutes and 40 seconds.

I call this solution "formal", since I assume (without a proof; as granted) that their rates can be summed in this job.


For a wide variety of similar solved joint-work problems with detailed explanations see the lessons
    - Using Fractions to solve word problems on joint work
    - Solving more complicated word problems on joint work
    - Selected joint-work word problems from the archive
in this site.

Read them and get be trained in solving joint-work problems.

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook under the topic "Rate of work and joint work problems" of the section "Word problems".



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