DS

[Jameschan168]

Hi all,

Can someone please help explain this problem?

S is a set of integers such that

i) if a is in S, then -a is in S, and
ii) if each of a and b is in S, then ab is in S.

Is -4 in S?

1) 1 is in S
2) 2 is in S

Stmt 1 is insufficient because 1 has nothing to do with -4 as the stmt does not provide any clues based on the 2 criteria above.

Stmt 2 is also insufficient because in order for -4 to be in S, either 4 (which fits the first criterion) or both 2 & -2 (which fits the second criteron) would need to be in S. Since stmt 2 only tells me that 2 is in S, but we don't know if -2 is also in S, why is the answer B?

[gabriel]

Hi all,

Can someone please help explain this problem?

S is a set of integers such that

i) if a is in S, then -a is in S, and
ii) if each of a and b is in S, then ab is in S.

Is -4 in S?

1) 1 is in S
2) 2 is in S

Stmt 1 is insufficient because 1 has nothing to do with -4 as the stmt does not provide any clues based on the 2 criteria above.

Stmt 2 is also insufficient because in order for -4 to be in S, either 4 (which fits the first criterion) or both 2 & -2 (which fits the second criteron) would need to be in S. Since stmt 2 only tells me that 2 is in S, but we don't know if -2 is also in S, why is the answer B?

the first statement says that if "a" is in s the "-a" is also there in s .. using that information we can see that if 2 is in s then -2 is also there in s ... and then from the second statement we know that since 2 and -2 is in s, 2*-2 is also there in s .. so -4 is in s .. hence the answer B ..

[kajcha]

Should be B

[kajcha]

Should be B