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ERRATA for Edition 4.2 Word Translations Study Guide

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atharshiraz
 Post subject: ERRATA for Edition 4.2 Word Translations Study Guide
 Post Posted: Thu Aug 04, 2011 4:01 pm 
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On page 191 I notice that the prob of Donald receiving Ropecia is given as 1/14 when it should be 1/13?

This is because the "remaining 13 patients" are given the Ropecia medicine? Is this an error on one's own part or a typo in the text?

One did not notice the error listed here but it covers only upto edition 4.1 :
http://www.manhattangmat.com/errata-wt-4ed.cfm

One searched for the errata and only found this link:
http://www.manhattangmat.com/errata.cfm

One has edition 4.2 (incidentally). There are some other errors one noticed which are obvious and minor so one didn't post a question but unsure about this one.
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tim
 Post subject: Re: ERRATA for Edition 4.2 Word Translations Study Guide
 Post Posted: Fri Aug 12, 2011 11:21 pm 
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nope, it's correct. your 1/13 probability is contingent on not being chosen for the first treatment, which will be true with probability 13/14. when you multiply your 1/13 by 13/14 you get a probability of 1/14. you appear to have done the problem a different way, but your method is valid as long as you remember to multiply by 13/14..

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atharshiraz
 Post subject: Re: ERRATA for Edition 4.2 Word Translations Study Guide
 Post Posted: Sat Aug 20, 2011 4:43 pm 
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Ok it was a minor error on one's own part. One feels that perhaps the following "missing" text would have helped one personally:

P(Donald receives Progaine) = 1/14 {0}

P(Donald receives Ropecia) =
P(Donald does NOT receive Progaine) x P(Donald receives Ropecia) {1}

Now P(Donald does NOT receive Progaine)= (13/14) {2}

Now that there are 13 remaining patients P(Donald receives Ropecia)= (1/13) {3}

Using [1],[2]and [3] P(Donald receives Ropecia) = (13/14)x(1/13)= 1/14 {4}

P(Donald receives Progaine OR Ropecia) = P(Donald receives Progaine) + P(Donald receives Ropecia)

From {4} and {0}

P(Donald receives Progaine OR Ropecia)= 1/14+ 1/14

One missed step 4. Thanks for pointing it out.
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tim
 Post subject: Re: ERRATA for Edition 4.2 Word Translations Study Guide
 Post Posted: Fri Sep 16, 2011 10:20 pm 
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Location: Southwest Airlines, seat 21C
no problem; that's what we're here for.. :)

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Manhattan GMAT Instructor
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