Standard Deviation-Gmat prep : PS Archive
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# Standard Deviation-Gmat prep

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Senior Manager
Joined: 23 May 2008
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Kudos [?]: 363 [0], given: 14

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10 Dec 2009, 11:27
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Need to know the approach to solve such questions.

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Senior Manager
Affiliations: PMP
Joined: 13 Oct 2009
Posts: 312
Followers: 4

Kudos [?]: 161 [4] , given: 37

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10 Dec 2009, 11:40
4
KUDOS
let m be mean and d be sd

we are given
m-2d = 58
m+3d=98

solving these we get m=74,d=8

some questions give elements of set (sometimes give mean and sd also) and ask how many are 1sd above mean or how many are 2sd below mean etc., questions.
u can answer such questions too with similar approach as for the question u posted
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Thanks, Sri
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Press +1 Kudos, if you think my post gave u a tiny tip

Senior Manager
Joined: 25 Jun 2009
Posts: 293
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Kudos [?]: 153 [0], given: 4

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14 Dec 2009, 08:36
Another way is to note that there are 5 deviations between 98 and 58, and 98-58=40, so 40/5 equalts 8. 58 + 2(8)= 74 or 98-3(8)=74
Re: Standard Deviation-Gmat prep   [#permalink] 14 Dec 2009, 08:36
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