If 20 men or 24 women or 40 boys can do a job in 12 days working for 8 hours a day, how many men working with 6 women and 2 boys take to do a job four times as big working for 5 hours a day for 12 days?
i cant figure out how exactly to use the (work=rate x time) approach. could you please provide a solution?
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- nimshad20
- Students
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- tommywallach
- Manhattan Prep Staff
- Posts: 1917
- Joined: Thu Mar 31, 2011 11:18 am
Hey Nimshad,
Well, I don't know if you copied this question down incorrectly or if the source is just bad, but I always encourage people to only post questions that are formatted correctly and grammatically coherent. Also, this question would never appear on the GRE, because it would require way longer than a real question on this subject ever requires, and I never like solving questions that wouldn't appear on the real test. But because the general concepts here are relevant, I'll talk it through. Still, in the future, do not post ANY questions from wherever you found this question.
The standard way to do a question like this is to choose a value for the work. In this case, we would want to choose the Lowest Common Multiple of 20, 24, and 40, so that everything remains an integer. Let's make the "job" equal to 120. And we'll put the time in hours to make life simpler:
Rate * Time * Workers = Work
Men 96 20 120
Women 96 24 120
Boys 96 40 120
I'm going to stop at this point, because as you can see, the numbers are horrific, which they would never be in a real question. But if you needed to solve, you could now use this equation to get the rate that each Man, Woman, and Boy has.
Then, we could solve. "Four times as big a job" would be 480 units, the time would be 60 ("5 hours a day for 12 day"), and we would use the rates we already determined for each woman and boy, and finally we could solve for how many men we would need.
Hope that all makes sense!
-t
Well, I don't know if you copied this question down incorrectly or if the source is just bad, but I always encourage people to only post questions that are formatted correctly and grammatically coherent. Also, this question would never appear on the GRE, because it would require way longer than a real question on this subject ever requires, and I never like solving questions that wouldn't appear on the real test. But because the general concepts here are relevant, I'll talk it through. Still, in the future, do not post ANY questions from wherever you found this question.
The standard way to do a question like this is to choose a value for the work. In this case, we would want to choose the Lowest Common Multiple of 20, 24, and 40, so that everything remains an integer. Let's make the "job" equal to 120. And we'll put the time in hours to make life simpler:
Rate * Time * Workers = Work
Men 96 20 120
Women 96 24 120
Boys 96 40 120
I'm going to stop at this point, because as you can see, the numbers are horrific, which they would never be in a real question. But if you needed to solve, you could now use this equation to get the rate that each Man, Woman, and Boy has.
Then, we could solve. "Four times as big a job" would be 480 units, the time would be 60 ("5 hours a day for 12 day"), and we would use the rates we already determined for each woman and boy, and finally we could solve for how many men we would need.
Hope that all makes sense!
-t
2 posts Page 1 of 1