Another one from official test prep

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Another one from official test prep

by sev » Wed Jun 06, 2007 12:12 pm
S is a finite set of numbers, Does S contain more negative numbers than positive numbers?

a) The product of all the numbers in S = -1200

b) There are 6 numbers in S


Now wouldnt it be if there are MORE negative numbers in set S than positive that the product of those numbers would be a negative?

I chose A

but the test says I'm wrong... and that the answer is E

why?!

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by mschling52 » Wed Jun 06, 2007 1:46 pm
(1) does not tell us anything about the relative number of positive or negative numbers. It just tells us that there is an odd number of negative numbers in the set. For example, if

S = {-3,10,40}, this satisfies (1), and there are more positive than negative, but if

S = {-3,-10,-40}, then (1) is satisfied, but there are more negative than positive.

(2) alone clearly does not do anything for us and combining (1) and (2), we could still have a situation like the one above.