Math-DS Problem-Number Line

You could have post this in DATA Sufficiency Forum.

Correct Answer is A.(Statement-1 alone is sufficient).

This is a Yes/No type data-sufficiency problem. Here we have to check whether we are getting UNIQUE (either YES or NO) or not.

Question: Is (s+t)=0 ?
To say YES, (s + t) should be equal to 0 (zero)
To say NO, (s+t) should not be equal to 0 (zero)

Statement-1:
The distance between S & 0 is the same as the distance between T & 0.
S -> 0 = T -> 0
take an example, if S->0 = -2 & T->0=2, then S+T = -2+2 = 0. Here Answer is YES.
Like this if we take the distance of S->0 and distance of T->0 is same. We will get UNIQUE answer YES. Hence, we can say Statement-1 is SUFFICIENT.

Statement-2:
0 is between S & T.
Here 0(zero) should present in between S & T. Its not necessary to be 0(zero) in middle of S & T.
Lets take examples,
if S=-2, T=3 :
Here 0 is in b/w S & T and (S+T) is not equal to 0(zero). Here it says NO.
If S=-2, T=-2:
Here 0 is in b/w S & T and (S+T) is equal to Zero(0). It say YES.
Hence we do not have UNIQUE answer, this statement-2 is NOT SUFFICIENT.

No need to check the Both the statements together.

HTH, GOOD LUCK,

Thanks,
Rajesh,
Loves GMAT....!!!