Statement 1:
0 could be exactly in the middle of r and s: YES
0 could be to the left of r: NO
Insufficient

Statement 2:
Two ways distance between t and -s could be equal to distance between t and r:

-s could be on r, which means 0 is exactly in the middle of r and s: YES
-s could be to the right of t: NO
Insufficient

Both statements together:
Since s must be to the right of 0 (from Stmt 1), then -s must be on r (from Stmt 2). Therefore 0 is exactly in the middle of r and s. Choose C.

-BM-

bluementor wrote: Statement 2:


-s could be on r, which means 0 is exactly in the middle of r and s: YES
-s could be to the right of t: NO
Insufficient

-BM-

I couldnt get the highlighted part pls explain

vivek.kapoor83 wrote:

bluementor wrote: Statement 2:


-s could be on r, which means 0 is exactly in the middle of r and s: YES
-s could be to the right of t: NO
Insufficient

-BM-

I couldnt get the highlighted part pls explain

Statement 2: The distance between t and r is the same as the distance between t and -s.

On the number line, point -s is not shown, but statement 2 tells us that -s could only be in one of the two positions (in order to keep the same distance as between t and r ) :

Case 1: If -s is on the same position as r, then distance between t and r will be the same as the distance between t and -s. In this case, 0 must be exactly halfway between -s and s (or halfway between r and s, since -s and r are the same points). So this case answers the question stem as a YES.

For example, if s = 3, then -s = -3 and 0 must be exactly halfway between s and -s.

Case 2: If -s is on the right of t, while still keeping the distance between t and r to be the same as the distance between t and -s, then 0 also will be to the right of t. In this case, 0 IS NOT halfway between r and s, and this answers the question stem as a NO.

Since both cases give us contradicting answers, this statement is insufficient. You will need the help of the 1st statement to kill one of these cases in order to answer the question stem definitely.

Hope this is clear now.

-BM-