GMAT prep

[rajt]

Please help me solve this. Thanks

[800GMAT]

A is insuff
1,2,3 Positive
-3,-2,-1 Negative

B is insuff
1,2,3,4 Positve
-1,2,3,4 Negative

A and B are suff
-4,-3,-2,-1
1,2,3,4


If The product of the greatest and smallest is positive and the there are odd number of integers only then you may get a negative product of integers. But stmt 2 eliminates that option and when combined with stmt 1 is sufficient. Hence C

[rajt]

here is what I do not understand.

Statement 2 states that the number of integers are even which means the set may consist of
{1, 2, -3, 4} or {-1,-2,3,4} or {1, -2, 3, 4, 5, 6} as long as the number of numbers are positive.

using 1 and the set {1,2,-3,4}
product of 1 and 4 = positive (product of lowest and highest integer)
product of 2 and -3 is negative,
so the end product is negative.

If I take a positive set of {1,2,3,4} for 2 then the product is positive.
So C is insufficient also.

What am I missing?

[800GMAT]

hi rajt

you said " using 1 and the set {1,2,-3,4}
product of 1 and 4 = positive (product of lowest and highest integer) "


however you cannot use the above set to satisfy stmt 1 and 2
because product of lowest and highest integer in your chosen set is -3*4 = -12 not 1*4 =4

[rajt]

Ok, now I understand. Thank you.
Raj