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Rate problem

by anniev2 » Fri Mar 13, 2009 10:32 am
From OG Math Review Section: If Machine X can produce 1,000 bolts in 4 hours and machine Y can produce 1,000 bolts in 5 hours, in how many hours can machines X and Y, working together at these constant rates, produce 1,000 bolts?

1/4 = 1/5 = 1/h
h = 2 2/9

Let's say, Machine X could produce 2,500 bolts in 6 hours. How Would the equation be set up?
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by sureshbala » Fri Mar 13, 2009 10:48 am
anniev2 wrote:From OG Math Review Section: If Machine X can produce 1,000 bolts in 4 hours and machine Y can produce 1,000 bolts in 5 hours, in how many hours can machines X and Y, working together at these constant rates, produce 1,000 bolts?

1/4 + 1/5 = 1/h
h = 2 2/9

Let's say, Machine X could produce 2,500 bolts in 6 hours. How Would the equation be set up?
As mentioned by you X produces 2,500 bolts in 6 hrs, i.e 5000 bolts in 12 hrs.

Similarly, Y produces 5000 bolts in 25 hrs.

So X and Y working together can produce 5000 bolts in 300/37 hrs.

Hence X and Y working together can produce 1000 bolts in 300/(37x5) = 60/37 hrs = 1 23/37 hrs
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by anniev2 » Fri Mar 13, 2009 10:52 am
Thank you! Rate problems are a weakness of mine and this helps me understand the strategy better.

Your logic was to make the amount of work done by both machines the same and then use the standard work/rate formula. Then you divided the result of the equation appropriately to provide the amoutn of work asked for in the question.
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