Guide 1, 4th ed., pg 40

[millen.paschich]

data sufficiency and sign question:

is the product of all of the elements in Set S negative?
1) all of the elements in Set S are negative
2) there are 5 negative numbers in Set S

my issue: i understand that statement 1) does not tell us how many numbers are in Set S, so we can not determine the sign. however, statement 2) tells us both how many numbers (5) and those numbers sign (negative). given that I believe zero can not be negative, why is the answer C, combined?

thanks

[apwiedmann]

The second statement does not tell us how many numbers are in the set. There are definitely 5 negative numbers in the set but there may be a lot of other numbers in the set, too. One of these numbers could be 0, which means that the product of all the elements would be neither positive nor negative, since 0 is "neutral". As a result, you need both statements to know that a) there is no 0 in the set and b) there is an odd number of negative numbers in the set.

It's a mean question. Would you mind having a look at my question, which I posted just before yours? My question also refers to the first guide. Thanks!

[tim]

good explanation!

[Rnaut]

I don't understand why is statement 2 " Insuffieceint " !

Statement 2 : There are 5 negative numbers in Set S

0 is neither negative nor positive. So, 0 should not be included in the Set S.
Considering that...product of all other ( non- zero) elements will result in a negative Set S.

Please explain where I went wrong. Thanks

[tim]

Where does it say 0 cannot be a member of the set?

[trapanister]

to be honest the same guide says: if the GMAt says that "there are 5 of something" the are EXACTLY 5 of something......

So, if we have 5 of something and the statement tell us that there are 5 negative why we must infer that we can have more of 5 elements ??'

I'm not sure why we have to consider also 0 among the numbers of the set........

As a matter of fact, the same guide says HOWEVER, why however and bla bla bla .....

regards .

[tim]

If the GMAT tells you there are 5 negative numbers, there are only 5 negative numbers. This does not preclude the possibility that there could be numbers that are 0 or positive..

[prepp]

Interesting question. So if it states that there are only 5 -ve numbers, then I guess 0 would not be a possibility of consideration, correct?

If the GMAT tells you there are 5 negative numbers, there are only 5 negative numbers. This does not preclude the possibility that there could be numbers that are 0 or positive..

[jnelson0612]

Interesting question. So if it states that there are only 5 -ve numbers, then I guess 0 would not be a possibility of consideration, correct?

If the GMAT tells you there are 5 negative numbers, there are only 5 negative numbers. This does not preclude the possibility that there could be numbers that are 0 or positive..

Yes, if the GMAT says that the set "consists of only five members, all of which are negative" then you're in the clear. Just watch the wording; the test writers love to trick us with stuff like this! :-)