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# Demystifying the Alligation Method of Weighted Averages

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Manager
Joined: 15 Sep 2009
Posts: 186
Demystifying the Alligation Method of Weighted Averages  [#permalink]

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08 Oct 2012, 06:48
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No doubt that there have been times when GMATClubbers deftly invoke the famous "Alligation Method" in solving complex weighted averages and other ratio-related problems. When learnt properly and practiced consistently, the Alligation Method can save up to a whole minute, valuable time that is better spent on monster problems as Quant difficulty increases on your adaptive tests.

So, I am posting a journal article from 1958 that gives a basic primer on the Alligation Method. The author is so cool that he actually cites his mother-in-law as a scientific source, describing her as "....Mrs. L. F. Wilcox could beat most modern mathematicians at arithmetic, which she learned in the grade schools in upper New York State...."

Enjoy, you nerds. And please give +1 Kudos, if you appreciate this.

PS. The main thing to remember is to reverse the ratio of the "distances" in order to find the ratio of the actual "quantities" present.

PPS. This post is purely an academic exercise and by no means a final authority on the beautiful concept that is the Alligation Method.

Cheers,
Der alte Fritz.
Attachments

File comment: An old school journey into the Alligation Method. Enjoy, folks.
Alligation arithmetic method.pdf [138.8 KiB]

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+1 Kudos me - I'm half Irish, half Prussian.
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Joined: 15 Sep 2009
Posts: 186
Re: Demystifying the Alligation Method of Weighted Averages  [#permalink]

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20 Feb 2013, 07:31
OG12 Problem Solving #223 (page 184) contains a problem that illustrates how EFFICIENT and TIME-SAVING the alligation method can be if deployed properly.

Regards,
Der alte Fritz.
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+1 Kudos me - I'm half Irish, half Prussian.
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Joined: 09 Sep 2013
Posts: 13411
Re: Demystifying the Alligation Method of Weighted Averages  [#permalink]

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28 Jan 2018, 02:39
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: Demystifying the Alligation Method of Weighted Averages   [#permalink] 28 Jan 2018, 02:39
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