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# Set K consists of a finite number of consecutive odd

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Director
Joined: 01 Apr 2008
Posts: 872

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Name: Ronak Amin
Schools: IIM Lucknow (IPMX) - Class of 2014
Set K consists of a finite number of consecutive odd [#permalink]

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25 Oct 2009, 01:13
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45% (01:22) correct 55% (01:25) wrong based on 145 sessions

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Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

(1) The average (arithmetic mean) of set K is –36.

(2) There are 8 numbers in set K.
[Reveal] Spoiler: OA

Kudos [?]: 861 [2], given: 18

Manager
Joined: 08 Oct 2009
Posts: 70

Kudos [?]: 32 [0], given: 6

Location: Denmark, Europe
Schools: Darden Class of 2012

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25 Oct 2009, 01:57
Economist wrote:
Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

(1) The average (arithmetic mean) of set K is –36.

(2) There are 8 numbers in set K.

(1) Insufficient. It could be (-37,-35), (-39,-37,-35,-33), etc.
(2) Insufficient. It could be any 8 (consecutive odd) numbers.

Combining information the set must be (-43,-41,-39,-37,-35,-33,-31,-29). The trick here is that they are consecutive odd numbers.

y-x is -29-(-43) = 14 and the answer is C.

Kudos [?]: 32 [0], given: 6

Math Expert
Joined: 02 Sep 2009
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Kudos [?]: 133146 [1], given: 12415

Set K consists of a finite number of consecutive odd [#permalink]

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25 Oct 2009, 14:12
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Economist wrote:
Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

(1) The average (arithmetic mean) of set K is –36.

(2) There are 8 numbers in set K.

Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

From the stem: first term x, las t term y --> as we have consecutive odd integers then y=x+2(n-1), where n is the number of terms in the set. --> y-x=x+2(n-1)-x=2(n-1)

Basically we should find the number of terms to calculate y-x.

(1) The average=-36, --> (x+y)/2=-36 --> (2x+2(n-1))=-36 --> x+n-1=-36. Multiple choices for x and n. Not sufficient.

The mean of consecutive ODD integers is ODD, when # of terms is ODD.
The mean of consecutive ODD integers is EVEN, when # of terms is EVEN.
So, as -36 is even, that is why the mean =(first term+last term)/2=-36

(2) n=8. --> y-x=2(n-1)=14. Sufficient

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Kudos [?]: 133146 [1], given: 12415

Manager
Joined: 08 Oct 2009
Posts: 70

Kudos [?]: 32 [0], given: 6

Location: Denmark, Europe
Schools: Darden Class of 2012

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25 Oct 2009, 15:23
D'oh!

I keep falling into these traps. Hopefully, practice will allow me to master them eventually...

Kudos [?]: 32 [0], given: 6

Intern
Joined: 16 Feb 2017
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Re: Set K consists of a finite number of consecutive odd [#permalink]

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30 Mar 2017, 15:22

Kudos [?]: 0 [0], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 42338

Kudos [?]: 133146 [0], given: 12415

Set K consists of a finite number of consecutive odd [#permalink]

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30 Mar 2017, 21:46
gardnej369 wrote:

There are 7 numbers in your set, not 8.
_________________

Kudos [?]: 133146 [0], given: 12415

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Joined: 14 Nov 2016
Posts: 1242

Kudos [?]: 1303 [0], given: 434

Location: Malaysia
Set K consists of a finite number of consecutive odd [#permalink]

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30 Mar 2017, 23:26
Bunuel wrote:
Economist wrote:
Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

(1) The average (arithmetic mean) of set K is –36.

(2) There are 8 numbers in set K.

From the stem: first term x, las t term y --> as we have consecutive odd integers then y=x+2(n-1), where n is the number of terms in the set. --> y-x=x+2(n-1)-x=2(n-1)

Basically we should find the number of terms to calculate y-x.

(1) The average=-36, --> (x+y)/2=-36 --> (2x+2(n-1))=-36 --> x+n-1=-36. Multiple choices for x and n. Not sufficient.

The mean of consecutive ODD integers is ODD, when # of terms is ODD.
The mean of consecutive ODD integers is EVEN, when # of terms is EVEN.
So, as -36 is even, that is why the mean =(first term+last term)/2=-36

(2) n=8. --> y-x=2(n-1)=14. Sufficient

Source : Magoosh
_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Kudos [?]: 1303 [0], given: 434

Math Expert
Joined: 02 Sep 2009
Posts: 42338

Kudos [?]: 133146 [0], given: 12415

Re: Set K consists of a finite number of consecutive odd [#permalink]

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30 Mar 2017, 23:34
ziyuen wrote:
Bunuel wrote:
Economist wrote:
Set K consists of a finite number of consecutive odd integers. If x is the smallest number in K and y is the greatest, then y - x =

(1) The average (arithmetic mean) of set K is –36.

(2) There are 8 numbers in set K.

From the stem: first term x, las t term y --> as we have consecutive odd integers then y=x+2(n-1), where n is the number of terms in the set. --> y-x=x+2(n-1)-x=2(n-1)

Basically we should find the number of terms to calculate y-x.

(1) The average=-36, --> (x+y)/2=-36 --> (2x+2(n-1))=-36 --> x+n-1=-36. Multiple choices for x and n. Not sufficient.

The mean of consecutive ODD integers is ODD, when # of terms is ODD.
The mean of consecutive ODD integers is EVEN, when # of terms is EVEN.
So, as -36 is even, that is why the mean =(first term+last term)/2=-36

(2) n=8. --> y-x=2(n-1)=14. Sufficient

Source : Magoosh

It's the formula of nth term of arithmetic progression. Check here: https://gmatclub.com/forum/math-sequenc ... 01891.html
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Kudos [?]: 133146 [0], given: 12415

Re: Set K consists of a finite number of consecutive odd   [#permalink] 30 Mar 2017, 23:34
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