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VP
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On the number line [#permalink]
 03 Apr 2006, 21:26
On the number line <-----------r-------s-----------t--------------->
Is zero halfway between r and s ?
1. s is to the right of zero.
2. The distance b/w t and r is the same as the distance b/w t and -s.
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Manager
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guessing its 'C'
St1 and St 2 together give us
r = -s
hence 0 is halfway between r and s
OA please
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Senior Manager
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lhotseface wrote: On the number line <-----------r-------s-----------t--------------->
Is zero halfway between r and s ?
1. s is to the right of zero.
2. The distance b/w t and r is the same as the distance b/w t and -s.
1, t can be to the right or left of zero->Ins
2, r=-s sufficient to answer the question
it's B
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Manager
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it's B
A --insufficient data
B t-r = t - (-s)
==> r =-s hence 0 is halfway between r and s
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GMAT Club Legend
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1) Not sufficient. r may also be to the right of 0.
2) This doesn't justify that 0 is between r and s.
I can have:
t-r = t+s
r = -s
So 0 must be in between
Ans B
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VP
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GMAT Prep says answer is C.
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SVP
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Me too selected B.
But I think it should be "C", how about this? (I many be wrong)
If we consider only statement2; r, s itself can be negative & -s can be positive, it means -s can be on the opposite side of r & s.
<-----------r-------s-----------t------------------ -s >
In this case, we can't say anything.
But statement 1 makes it clear that 0 lies somewhere before 's', hence "C" makes sense.
How does this sound?
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Manager
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Answer B, i.e. stmnt 2 by itself is sufficient.
The stems basically asks is s = -r ? In other words, if zero is exactly between the two, then one is the negative value of the other. Draw a number line to visualize this.
Stmnt 1:
Nothing is said about the property of r. Insufficient.
Stmnt 2:
The distance b/w t and r is the same as the distance b/w t and -s. In other words,
t - r = t - (-s)
t - r = t + s
- r = s
s = -r
Sufficient.
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VP
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I eliminated this possibility in the test, but I think that was due to test pressure. Your logic looks correct...B gives two possibilites => r,s < 0 or r<0 and s > 0.
vivek123 wrote: Me too selected B.
But I think it should be "C", how about this? (I many be wrong)
If we consider only statement2; r, s itself can be negative & -s can be positive, it means -s can be on the opposite side of r & s.
<-----------r-------s-----------t------------------ -s >
In this case, we can't say anything.
But statement 1 makes it clear that 0 lies somewhere before 's', hence "C" makes sense.
How does this sound?
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Manager
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How can B give two possibilities when stmnt 2 makes it clear that either s is the negative value of r or the other way around?
Confused 
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VP
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s = -5 => -s = 5,
r = -5 and t = 0.......................One possibility
s =5, r = -5 and t = 10............Second possibility
Matador wrote: How can B give two possibilities when stmnt 2 makes it clear that either s is the negative value of r or the other way around? Confused |
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Manager
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I think the answer should be B.
From statement 2,
distance between t and r = distance between t and -s
=> t-r = t+s
=> r+s = 0
Hence, if r+s = 0, answer holds good and we need not worry about the sign of t.
lhotesface,
your first example, r = -5, s = -5 and t = 0
is not correct because it does not satisfy second statement.
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VP
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lhotseface wrote: s = -5 => -s = 5,
r = -5 and t = 0.......................One possibility
lhotseface, vivek and others...
s =5, r = -5 and t = 10............Second possibility
What if t =0 and r=5 and s =5... that leads us to E!!
My take on this:
If we are shown 3 numbers on a number line at distinct locations, we should assume that they are not equal and that they have a relationship defined by their corresponding locations. So from the picture I would assume r < s < t
That leaves us with B as the unambiguous answer. Any thoughts?
_________________
"To dream anything that you want to dream, that is the beauty of the human mind. To do anything that you want to do, that is the strength of the human will. To trust yourself, to test your limits, that is the courage to succeed."
- Bernard Edmonds
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VP
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It does since distance b/w t(0) and -s(5) is 5 and the distance b/w t and r is 5 ( distances are always absolute ).
chuckle wrote: I think the answer should be B.
From statement 2,
distance between t and r = distance between t and -s
=> t-r = t+s
=> r+s = 0
Hence, if r+s = 0, answer holds good and we need not worry about the sign of t.
lhotesface,
your first example, r = -5, s = -5 and t = 0
is not correct because it does not satisfy second statement.
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VP
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That is what I thought on the test...but the OA is C from GMATPrep. (?!)
In the real exam, I am going to assume such ambiguous questions are experimental, pick a reasonable choice and move on.
giddi77 wrote: lhotseface wrote: s = -5 => -s = 5,
r = -5 and t = 0.......................One possibility
lhotseface, vivek and others...
s =5, r = -5 and t = 10............Second possibility What if t =0 and r=5 and s =5... that leads us to E!! My take on this: If we are shown 3 numbers on a number line at distinct locations, we should assume that they are not equal and that they have a relationship defined by their corresponding locations. So from the picture I would assume r < s < tThat leaves us with B as the unambiguous answer. Any thoughts? |
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VP
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giddi77 wrote: What if t =0 and r=5 and s =5... that leads us to E!! t cannot be zero since s is right to the zero. giddi77 wrote: If we are shown 3 numbers on a number line at distinct locations, we should assume that they are not equal and that they have a relationship defined by their corresponding locations. So from the picture I would assume r < s < t IMO, in GMAT, unless figures are not supported by the facts, figures are not drawn to scale. therefore, it is possible that the value of r, s and t could be anything. lhotseface wrote: On the number line <-----------r-------s-----------t--------------->
Is zero halfway between r and s ?
1. s is to the right of zero.
2. The distance b/w t and r is the same as the distance b/w t and -s.
from i, s is +ve. so not suff.
from ii, if the distance between t and r is the same as the distance between t and -s, then r must equal to s. cuz the distance between any given points is absolute.
so to have the distance between t and s = distance between t and -s, s and r must have the same value. if so then we can say that o is not a halfway between r and s.
so go with B.
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Senior Manager
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opps i rushed towards the ans. I wrongly read the question 
1 helps answering the question but is not sufficient
2 alone answers the question
I go with answer B
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Intern
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From 1) We know that t-r=t-(-s) => s=-r But it's possible that s=-r=0 so we can't say whether 0 on a halfwat
From 2) we know that C is NOT zero thus from s=-r we know that r is a not zero negative number while C is not zero positive number
So it's C
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VP
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Lets see what Honghu and laxi say on this one. 
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close
