On the number line shown, is zero halfway between a and b
<-----------------a---------b----c----------->
1) b is to the right of zero.
2) The distance between c and a is the same as the distance between c and -b.
OA: C
Easy but Tricky
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- limestone
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1. O can either be:
0<a<b
a<0<b
Then insuff.
2.
The distance between c and b is smaller than the distance between c and a ( as given information)
Then the distance between c and b is smaller than the distance between c and -b
However, the distance between 0 and b is equal to the distance between 0 and -b.
Then b<c<0<-b as shown below:
<-------------a---b------------c---0-------------(-b)------->
To make it clearer,
let's call length of "bc" : x
that of "-bc": y
Ob =O-b = z
As length of O-b=length of ca and length of ca > than length of cb,
then z>x, or O is to the right of c.
If 0>c then obviously:
0>c>b>a
Then Zero is not halfway between a and b.
Suff.
Pick B
0<a<b
a<0<b
Then insuff.
2.
<--------------a------b----------c--------------(-b)------------>The distance between c and a is the same as the distance between c and -b.
The distance between c and b is smaller than the distance between c and a ( as given information)
Then the distance between c and b is smaller than the distance between c and -b
However, the distance between 0 and b is equal to the distance between 0 and -b.
Then b<c<0<-b as shown below:
<-------------a---b------------c---0-------------(-b)------->
To make it clearer,
let's call length of "bc" : x
that of "-bc": y
Ob =O-b = z
As length of O-b=length of ca and length of ca > than length of cb,
then z>x, or O is to the right of c.
If 0>c then obviously:
0>c>b>a
Then Zero is not halfway between a and b.
Suff.
Pick B
"There is nothing either good or bad - but thinking makes it so" - Shakespeare.
- shovan85
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I agree. But Sanju09 has different theory here https://www.beatthegmat.com/best-approac ... 67985.html.limestone wrote:1. O can either be:
0<a<b
a<0<b
Then insuff.
2.<--------------a------b----------c--------------(-b)------------>The distance between c and a is the same as the distance between c and -b.
The distance between c and b is smaller than the distance between c and a ( as given information)
Then the distance between c and b is smaller than the distance between c and -b
However, the distance between 0 and b is equal to the distance between 0 and -b.
Then b<c<0<-b as shown below:
<-------------a---b------------c---0-------------(-b)------->
To make it clearer,
let's call length of "bc" : x
that of "-bc": y
Ob =O-b = z
As length of O-b=length of ca and length of ca > than length of cb,
then z>x, or O is to the right of c.
If 0>c then obviously:
0>c>b>a
Then Zero is not halfway between a and b.
Suff.
Pick B
Can you please have a look there?
- limestone
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I have just looked at Sanju09's theory. And it's correct.
I'll give out 2 example that make (2) insuf :
1st one:
a = -4; b =-2, c=-1, -b = 2
The distance between a and c is 3 units of length.
The distance between -b and c is 3 units of length too.
In this case a<b<0
2nd one:
a = -4, b = 4, c = 1, -b = -4
The distance between a and c is 5 units of length.
The distance between -b and c is 5 units of length too.
In this case a<0<b
From the above examples, 2 alone is not suf.
1 alone is obviously not suf.
However, when combining with 2, (1) will eliminate the case that a<b<0 ( where b is to the left of zero). Thus the combined condition forces a and b to such an order of: a<0<b. Then 1 & 2 together is suff.
C should be the answer.
Thanks Sanju09 for an interesting and tricky question and shovan85 for reposting this question.
I'll give out 2 example that make (2) insuf :
1st one:
a = -4; b =-2, c=-1, -b = 2
The distance between a and c is 3 units of length.
The distance between -b and c is 3 units of length too.
In this case a<b<0
2nd one:
a = -4, b = 4, c = 1, -b = -4
The distance between a and c is 5 units of length.
The distance between -b and c is 5 units of length too.
In this case a<0<b
From the above examples, 2 alone is not suf.
1 alone is obviously not suf.
However, when combining with 2, (1) will eliminate the case that a<b<0 ( where b is to the left of zero). Thus the combined condition forces a and b to such an order of: a<0<b. Then 1 & 2 together is suff.
C should be the answer.
Thanks Sanju09 for an interesting and tricky question and shovan85 for reposting this question.
"There is nothing either good or bad - but thinking makes it so" - Shakespeare.