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RonPurewal
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Post subject:  Posted: Thu Nov 20, 2008 8:32 am |
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| ManhattanGMAT Staff |
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Posts: 7146
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[quote="RR"I feel that zero can be on the list. But the good part is, the answer does not change if zero is there. If zero is there, the product of all numbers in the list will be zero and hence positive.[/quote]
whoa, back up that train.
kill that noise.
ZERO IS NOT POSITIVE.
it's not negative, either.
zero is neither positive nor negative.
you know this, by the way, whether you realize it or not. remember all your old trusty rules, such as "negative times positive = negative"? yeah, those would fall apart if zero were considered positive. for instance, consider -6 x 0 = 0.
zero is, however, even (as are things like -2, -4, and so on).
--
the good thing is, though, that zero can't be in the list under the demands of statement #1 (because, under statement #1, the numbers are either all positive or all negative). therefore, you can forget about zero as soon as you ascertain that statement #2 is insufficient.
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kourakis
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Post subject: Re: Posted: Sat Aug 20, 2011 10:57 am |
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Zero is the third sign! neither positive, nor negative. If it were an option, the answer would be E. But due to the problem's constraints, zero is not an option.
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RonPurewal
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Post subject: Re: Re: Posted: Thu Aug 25, 2011 3:57 am |
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| ManhattanGMAT Staff |
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kourakis wrote: Zero is the third sign! neither positive, nor negative. yep. incidentally, this sort of thing is a good illustration of why it's important not to become too obsessed with “advanced” concepts. the people i see messing up this kind of thing the most are, in many cases, the same people who are always looking for the hardest problems and nothing else.
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shawnchacko06
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Post subject: Re: A certain list consists of several different integers Posted: Thu Sep 01, 2011 3:17 am |
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Posts: 2
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Why shouldnt we consider an option having only 2 integers?
Example:
1) -1, -3=>
a) product of greatest and smallest is postive =>3
b) There is even number of integers =>2 integers
2) 1, 3 =>
a) prodcut of greatest and smallest is postive => 3
b) There is even number of integers =>2 integers
Please let me know if i am missing something.
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JohnHarris
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Post subject: Re: A certain list consists of several different integers Posted: Thu Sep 01, 2011 2:21 pm |
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Posts: 38
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An ordered list is not required. We have determined that either both the largest and smallest number are positive OR the largest and smallest number are negative.
In the situation where both are positive, since the smallest is positive all of them must be positive. The product of positive numbers is positive.
In the situation where both are negative, since the largest number is negative all of them must be negative. The product of an even number of negative numbers is positive.
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shawnchacko06
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Post subject: Re: A certain list consists of several different integers Posted: Fri Sep 02, 2011 12:09 am |
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Posts: 2
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RonPurewal
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Post subject: Re: A certain list consists of several different integers Posted: Sat Sep 03, 2011 9:25 pm |
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Posts: 7146
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