Integer

[billyr]

A certain list consist of several different integer. Is the product of all integer in the list is positive?

(1) The product of the greatest and smallest in the list is positive
(2) There is an even number of integer in the list

The answer is c(need both statement), but why c?

Thanks

[DanaJ]

Here's how I see it:
1. tells us that (smallest)*(greatest) is positive means that:
a. both are positive and since they are the "ends" of the series, that makes all the numbers positive. In this case, the product will be positive
b. both are negative, making all of the numbers negative. However, in this case we cannot tell if the product is positive, since we don't know if we have an even or an odd "number" of numbers. Take for example: -5, -4, -3. While it's true that (-5)*(-3) is positive, that cannot be said about the product of the three.

2 doesn't help much. All numbers could be positive, or you could have smth like: -5, 3, 4, 5.

Put the two together and you "eliminate" that weak spot in case b from stmt 1: even if all numbers are negative, they "cancel" each other's minuses. So the OA is ok.

[crazy4gmat]

gr8 expln.