OG 12 Question

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OG 12 Question

by parulmahajan89 » Sun Nov 17, 2013 9:51 pm
Of the four numbers represented on the number line
above, is r closest to zero?
(1) q = -s
(2) -t < q


q r s t( This is the order of numbers) on number line.

Can someone please help in explaining how to approach this question in timely manner?

Thanks
Source: — Data Sufficiency |

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by theCodeToGMAT » Sun Nov 17, 2013 10:11 pm
To find: r closest to zero

We know the exact pattern: q r s t

Statement 1:
Image
q = -s
this means that q & s are on opposite sides of "0"
We know that "r" lies between Q & S.. So, that means "r" is closest to "0"
SUFFICIENT


Statement 2:
Image
-t < q
We know that "t" is the biggest value of the sequence (magnitude wise)
We are not given whether q r s t are positive or negative..
INSUFFICIENT

ANSWER [spoiler]{A}[/spoiler]
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by Brent@GMATPrepNow » Mon Nov 18, 2013 7:11 am
Image
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.
So, we get something like this: q.....0.....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 Mathsbuddy » Fri Nov 22, 2013 9:40 am
q r s t

Of the four numbers represented on the number line, is r closest to zero?

(1) q = -s gives us: -s r s t
-s and s are equidistant from 0, and r is in between, so it has to be closer to zero: SUFFICIENT.

(2) -t < q (i.e. t > -q) gives us: -t q r s t, but we have no information on the distribution of r and s, so INSUFFICIENT

Combined:
(2) -t < q (i.e. t > -q = s) gives us: -s r s t : SUFFICIENT. YES.

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by GMATGuruNY » Fri Nov 22, 2013 12:37 pm
Image

q, r, s and t 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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