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Michael and Adam

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by truplayer256 » Fri Jul 10, 2009 5:26 pm
Micheal and Adam can do together a piece of work in 20 days. After they have worked together for 12 days Micheal stops and Adam completes the remaining work in 10 days. In how many days Micheal complete the work separately?

I got 100 days. I don't have an OA so can you guys tell me if I'm right?

My work:

They work together for a total of 12 days and they can finish the piece of work in 20 days, so, so far, they've completed 12/20 or 3/5 of the piece of work. Only 2/5 of the work remains and Adam can complete this work in 10 days working alone. So, if Adam can complete 2/5 of the work in 10 days, he can finish all the work in 10*5/2= 25 days.

1/25+1/M=1/20

1/20-1/25=1/M

(25)(20)/(5)=M

100=M
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by ssmiles08 » Fri Jul 10, 2009 6:57 pm
I got 100 as well. I solved it the exact same way you solved it.
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by shibal » Sat Jul 11, 2009 6:20 am
so did I.... i even double chcked it (adding M and A) and got 20 days....
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by truplayer256 » Sat Jul 11, 2009 8:03 am
Alright, cool. Thanks guys.
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by VP_Jim » Sat Jul 11, 2009 9:10 am
I got 100 as well, but did it a little differently.

On work problems such as this, I often like to "plug in" a value for the job. In this case, I said that the job was to make 120 pizzas. I chose 120 since it works nicely with 10, 12, and 20.

Anyway, as described above, if they worked together for 12 days, they are 3/5 done with the job. So, Adam has to do 2/5 of the job by himself. 2/5 of 120 is 48. According to the problem, it will take Adam 10 days to finish the job (48 pizzas), so Adam's "rate" is 4.8 pizzas per day.

We also know that their combined rate is 6 pizzas per day since it takes them 20 days to make 120 pizzas when working together. So, if Adam's rate is 4.8, then Michael's rate must be 1.2 pizzas per day.

Now, if Michael makes 1.2 pizzas per day, it will take him 100 days to make 120 pizzas.

That seems pretty long when it's all typed out, but once you get the hang of it it's actually pretty easy. Good question!
Jim S. | GMAT Instructor | Veritas Prep
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by frank1 » Mon May 31, 2010 7:14 pm
truplayer256 wrote:Micheal and Adam can do together a piece of work in 20 days. After they have worked together for 12 days Micheal stops and Adam completes the remaining work in 10 days. In how many days Micheal complete the work separately?

I got 100 days. I don't have an OA so can you guys tell me if I'm right?

My work:

They work together for a total of 12 days and they can finish the piece of work in 20 days, so, so far, they've completed 12/20 or 3/5 of the piece of work. Only 2/5 of the work remains and Adam can complete this work in 10 days working alone. So, if Adam can complete 2/5 of the work in 10 days, he can finish all the work in 10*5/2= 25 days.

1/25+1/M=1/20

1/20-1/25=1/M

(25)(20)/(5)=M

100=M
i find language of question bit confusing?
is question asking
how long it would have taken micheal to complete the remaing or total task if it was done by micheal instead of adam
or is it asking
working capacity of micheal?
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