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ashish.jere

Post subject: For a finite sequence of non zero numbers, the number Posted: Fri Jul 17, 2009 3:35 am 


Students 

Posts: 77

For a finite sequence of non zero numbers, the number of variations in the sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence 1,3,2,5,4,6?
1)1 2)2 3)3 4)4 5)5
i remember when i did this problem for the first time, i rearranged them in ascending order and got the wrong answer. what part of the question should stop me from doing such mistakes?





RonPurewal

Post subject: Re: sequence Posted: Tue Jul 21, 2009 6:10 pm 


ManhattanGMAT Staff 

Posts: 13028

ashish.jere wrote: i remember when i did this problem for the first time, i rearranged them in ascending order and got the wrong answer. what part of the question should stop me from doing such mistakes? you're asking the wrong question. a SEQUENCE, by default, is IN ORDER. you cannot change the order of a sequence unless you are explicitly instructed to do so by the problem.if the profits of a business, in sequence, for a few consecutive years are $1 million, $4 million, $2 million, $3 million, and $0, then you can't just rearrange those into increasing order. the question is, "is there anything here that TELLS me to reorder the sequence?" the answer is no. therefore, you don't reorder the sequence. that's pretty much it.
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chuckberry007

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Aug 06, 2009 3:01 am 


Students 

Posts: 22

Hi,
Is the answer B.
My working:
1* 3 = VE
5*4 = VE
Number of variation = 2
hence (B).





elaine1920

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Aug 06, 2009 2:23 pm 


Students 

Posts: 8

Chunkberry, I think the answer is C, three. You missed one pair. (1, 3), (3,2) and (5, 4).





adam.roffman

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Aug 06, 2009 2:26 pm 


Students 

Posts: 6

I'd go with C. My working: 1*3 = negative 3*2 = negative 5*4 = negative





sharath.nair

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Aug 06, 2009 3:51 pm 


Students 

Posts: 7

What about 3*2? I say the answer is C.





Ben Ku

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Mon Aug 17, 2009 8:15 pm 


ManhattanGMAT Staff 

Posts: 818

ashish.jere, I think the responses answer your question.
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karanrob

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Dec 01, 2011 1:44 am 


Students 

Posts: 14

Questions such as the one mentioned above clearly indicate the "hey did you go through the definition of Sequences" and imprint the idea in your head. Oh also, never be creative and never assume, so if it says "sequence" you may not re arrange it. There are 1000 other questions they could form to test ones ability, such questions just show their lack of interest.
As a student preparing for the GMAT, I would like to be outwitted, then be cheated (If I may put it in that sense).





tarunlakhani

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Fri Dec 02, 2011 8:03 am 


Students 

Posts: 3

Oh! God What is dis question. I got dis in my GMAT Prep and it took me ages to understand it. It was the 3rd ques in quant sec. It scared me so much that I ended up doing very bad in my Prep test.
Can someone explain in detail what is this ques saying?





RonPurewal

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Fri Dec 09, 2011 4:56 am 


ManhattanGMAT Staff 

Posts: 13028

tarunlakhani wrote: Oh! God What is dis question. I got dis in my GMAT Prep and it took me ages to understand it. It was the 3rd ques in quant sec. It scared me so much that I ended up doing very bad in my Prep test.
Can someone explain in detail what is this ques saying? hi  two things, please (1) please write without abbreviations ("dis", etc.) that make your text difficult to understand; (2) please ask a more specific question. i.e., what did you understand? what didn't you understand? with what particular part of the wording did you have trouble? this is a problem in which an unfamiliar term ("variations in sign") is given a definition directly in the problem statement, so, it's essential that we understand exactly what gave you trouble. thanks.
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amit1234

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Wed Jan 11, 2012 8:56 am 


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Posts: 25





tim

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Sun Jan 15, 2012 4:10 pm 


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Posts: 4986 Location: Southwest Airlines, seat 21C

yes, if 6 showed up in the sequence followed immediately by 1, that would be a pair as defined in the problem..
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shubham_sagijain

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Thu Mar 01, 2012 5:48 pm 


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Posts: 27

Tim,
So, the answer should be C (i.e 3 variations). Am i right ?
Thanks, Shubh





RonPurewal

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Sat Mar 03, 2012 8:47 am 


ManhattanGMAT Staff 

Posts: 13028

shubham_sagijain wrote: Tim,
So, the answer should be C (i.e 3 variations). Am i right ?
Thanks, Shubh yes.
_________________ Pueden hacerle preguntas a Ron en castellano Potete fare domande a Ron in italiano On peut poser des questions Ã£ Ron en franÃ§ais Voit esittÃ¤Ã¤ kysymyksiÃ¤ Ron:lle myÃ¶s suomeksi
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shubham_sagijain

Post subject: Re: For a finite sequence of non zero numbers, the number Posted: Sat Mar 03, 2012 8:49 am 


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Posts: 27

RonPurewal wrote: shubham_sagijain wrote: Tim,
So, the answer should be C (i.e 3 variations). Am i right ?
Thanks, Shubh yes. Thanks Ron !





