Machines X and Y run simultaneously at their respective : GMAT Data Sufficiency (DS)
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# Machines X and Y run simultaneously at their respective

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Machines X and Y run simultaneously at their respective [#permalink]

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15 Mar 2012, 02:37
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Machines X and Y run simultaneously at their respective constant rates. If machine X produces 400 bolts per hour, how many bolts do machines X and Y produce per hour?

(1) Machine X takes twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number of bolts.
(2) Machines X and Y produce bolts at the same rate.

Guys - I always struggle to do these questions. Can someone please let me know the step by step approach i.e. what should I be thinking as 1st step when I see this type of rate question.
[Reveal] Spoiler: OA

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Re: Machines X and Y run simultaneously at their respective [#permalink]

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15 Mar 2012, 02:51
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Machines X and Y run simultaneously at their respective constant rates. If machine X produces 400 bolts per hour, how many bolts do machines X and Y produce per hour?

(1) Machine X takes twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number of bolts --> since machine X needs twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number, then the rates of X and Y are the same: both produce 400 bolts per hour, (working together they need 1/2 hours to produce 400 bolts). Sufficient.

(2) Machines X and Y produce bolts at the same rate. We know the rates of both machines. Sufficient.

Check these links for more on this topic:
two-consultants-can-type-up-a-report-126155.html?hilit=know%20rate%20work%20reciprocal#p1030079

Hope it helps.
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Re: Machines X and Y run simultaneously at their respective [#permalink]

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30 May 2013, 03:56
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

All DS work/rate problems to practice: search.php?search_id=tag&tag_id=46
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31 May 2013, 04:24
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Asked what is Combined rate i.e Rc = Rx + Ry

Given Rx = 400 , only unknown is Ry , i.e question is asking what is Ry?

1.) from statement 1 2Rx = Rx + Ry

therefore Rx =Ry

so we have value of Rc

2.) Rx= Ry given

this is how i calculated
Ans is D

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Re: Machines X and Y run simultaneously at their respective [#permalink]

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10 Oct 2016, 08:45
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Machines X and Y run simultaneously at their respective   [#permalink] 10 Oct 2016, 08:45
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