daretodream wrote:On the number line shown, is zero halfway between r and s ?

----r----s--t---------

1) s is to the right of zero
2) The distance between t and r is the same as the distance between t and -s

1) is insufficient

2) t-r = t- (-s)

=> r = -s


Now there are two cases when s is greater than zero and when s is less than zero

s cannot be less than zero because in that case r is greater than 0 ;it violates the depiction in the number line (I am assuming that the depiction of the number line is also given in the question)

Zero is in the middle - Sufficient

daretodream wrote:On the number line shown, is zero halfway between r and s ?

----r----s--t---------

1) s is to the right of zero
2) The distance between t and r is the same as the distance between t and -s

Statement 1) Only tells us S is positive but nothing about its distance and nothing about R.
insuff
Statement 2) This tells us that -S=R but it doesn't tell us anything to either S or R in relation to 0.
insuff

Statement 1+2) This tells us S is positive. Hence -S is negative. Since -S=R then the distance between S and 0 is the same as -S and 0 and hence R and 0.

IMO C

daretodream wrote:On the number line shown, is zero halfway between r and s ?

----r----s--t---------

1) s is to the right of zero
2) The distance between t and r is the same as the distance between t and -s

St.1) s is to the right of zero but 0 can be left or right of r ================not suff.
St.2) t-r = t -(-s) ie.e -s is a point at r so surely 0 lies at the midpoint of r and s
suff .
Ans B

thephoenix wrote:

daretodream wrote:On the number line shown, is zero halfway between r and s ?

----r----s--t---------

1) s is to the right of zero
2) The distance between t and r is the same as the distance between t and -s

Statement 1) Only tells us S is positive but nothing about its distance and nothing about R.
insuff
Statement 2) This tells us that -S=R but it doesn't tell us anything to either S or R in relation to 0.
insuff

Statement 1+2) This tells us S is positive. Hence -S is negative. Since -S=R then the distance between S and 0 is the same as -S and 0 and hence R and 0.

IMO C

phoenix I think if s is in left of 0 also then -s will be on right
whatever be the case 0 will lie between s and -s and hence s and r....