DS : GMATPrep Question 2

[simplyjat]

This is a question form GMATprep and I got it wrong.

[hopetobeat]

This is a question form GMATprep and I got it wrong.

IMO-- B

STMT 1 -- e.g. 3,0,0 and 0,0,0 --> NOT sufficient
STMT 2 -- must be all 0s to suffice --> Yes

[bickram]

This is a question form GMATprep and I got it wrong.

I think the answer is C. isn't it?
What is the answer?

[codesnooker]

I think answer is C,

Let check with the list {-1, 0, +1}

Condition B: not suffice; So condition A should also be suffice in order to make all the elements equal to zero.

[simplyjat]

OA is B
and the explanation given by hopetobeat is correct...

[codesnooker]

Ya, you correct!

[Stuart@KaplanGMAT]

I think answer is C,

Let check with the list {-1, 0, +1}

Condition B: not suffice; So condition A should also be suffice in order to make all the elements equal to zero.

Statement (2) says:

the sum of ANY two numbers in the set is 0.

In other words, one has to be able to look at any randomly selected pair of numbers and they have to sum to 0.

So, if we look at your list, if we select 0 and 1 we don't get a sum of 0. Therefore, the list you've chosen is impermissible (i.e it violates the rule, so you're not allowed to choose it).

The only way to guarantee that the sum of any two numbers is 0 is to choose all "0"s.

For statement (1) on the other hand, as long as every number except for one of them is 0, the rule will be satisfied.

For example, if we choose the list {0, 0, 1), every possible pair of numbers (0/0, 0/1, 1/0) has a product of 0. So it's possible to choose a set that has a non-zero member.

(2) is sufficient but (1) isn't: choose B.