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by vinay1983 » Tue Sep 17, 2013 6:01 am
Source : OG 13 OA A

Can we assume the line to be equally spaced?

In the OG explanation, it is said that "since S lies to the right it is positive and Q negative!

Aren't the 2 long drawn inference in practicality.

Unless specified how can we say that the points are equally faced?
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You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!
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by theCodeToGMAT » Tue Sep 17, 2013 6:38 am
No, we cannot assume that the variables are equally spaced; but, accept the variables sequence alignment i.e q...r.....s.....t

Considering Question Stem & Statement 1, assume:
q = -4
s = 4
t = 6
Since, according to the Q stem R lies between q & s hence, r's value would be between -4 & 4 .. So closest.. SUFFICIENT

Statement 2:
We don't know the position of q.. it can be either on left side of "0" or on right side "s" .. So we cannot comment whether "r" is closest or not. Insufficient.

So, Answer is [A]



vinay1983 wrote:Source : OG 13 OA A

Can we assume the line to be equally spaced?

In the OG explanation, it is said that "since S lies to the right it is positive and Q negative!

Aren't the 2 long drawn inference in practicality.

Unless specified how can we say that the points are equally faced?
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by Brent@GMATPrepNow » Tue Sep 17, 2013 7:17 am
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Of the four numbers represented on the number line, is r closest to zero?

(1) q = -s
(2) -t < q
Target question: Is r closest to zero?

Statement 1: q = -s
This tells us that q and s are on opposite sides of zero (i.e., one is positive and one is negative) AND it tells us that q and s are the same distance from zero.
For example, if q = 3, then s = -3, and if q = -8, then s = 8.
This tells us that zero is halfway between q and s.
Since r is between points q and s, r must be the closest point to zero
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: -t < q
There are several sets of values that satisfy this condition. Here are two:
Case a: q = -1, r = 0, s = 1 and t = 2, in which case r IS the closest to zero
Case b: q = 0, r = 1, s = 2 and t = 3, in which case r is NOT the closest to zero
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

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by GMATGuruNY » Tue Sep 17, 2013 8:09 am
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q, r, s and t do not have to be equally spaced, but they must be in the order shown.

Statement 1: q = -s
Case 1: s=1, q=-1
q=-1.....0.....s=1.....t
Here, r must be in the RED PORTION between q and s.
Since the red portion includes 0, r will be closest to 0.

Case 2: s=10, q=-10
q=-10...............0...............s=10.....t
Once again, r must be in the RED PORTION between q and s.
Since the red portion includes 0, r will be closest to 0.

In every case, r will be in the red portion between q and s -- the portion that includes 0.
Thus, r will always be closest to 0.
SUFFICIENT.

Statement 2: -t < q
If t=10, then q>-10.
Thus, the number line could look like this:
q=-9...........r..........s............t=10.
No way to determine whether r or s is closest to 0.
INSUFFICIENT.

The correct answer is A.
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