m9 q34

sset009 · **Posted:** Fri Jul 18, 2008 1:44 am

A , B , and C are points on the plane. Is AB \lt 10 ?

1. AC + BC = 10
2. AB + AC \gt 10

[Reveal] Spoiler: OA

E

Source: GMAT Club Tests - hardest GMAT questions

Couldnt understand the official explanation

sset009 · **Posted:** Fri Jul 18, 2008 3:52 am

but how do u know its a triangle?
and not on a straight line?

jallenmorris · **Posted:** Fri Jul 18, 2008 7:19 am

I am thinking E.

I agree, neither by itself gives you enough information. We're really only discussing C or E.

So, if you take the two statements and you make them AC + BC = AB + AC ( and I realize #2 is >, not =, but follow me for a second), you get
AC + BC = AB + AC The AC on each side cancels out, so you have BC = AB. Because AB + AC is actually Greater than, since AC is the same, the difference must be in AB, which must be larger than BC, but we don't know how much larger.

We know AC is less than 10 because AC + BC = 10. A number + another number will always be less than the sum of the two numbers (as long as they're both positive).

AC can be anything up to (but not including) 10. It could be 9.9999999999999999999, and BC = 10 minus that :-D

(i'm not counting the 9's).

Because AB + AC > 10, AB + AC = 300 or AB + AC = 10.1. The point is we just don't know and together they're insufficient.

sset009 wrote:

A , B , and C are points on the plane. Is AB \lt 10 ?

1. AC + BC = 10
2. AB + AC \gt 10

(C) 2008 GMAT Club - m09#34

* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient
* Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient
* BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
* EACH statement ALONE is sufficient
* Statements (1) and (2) TOGETHER are NOT sufficient

Couldnt understand the official explanation

maratikus · **Posted:** Wed Oct 01, 2008 5:16 am

dczuchta wrote:

A ,B , and C and are points on the plane. Is AB<10 ?

1) AC+BC=10
2) AB+AC >10

Answer: E

Can someone pls explain this DS answer to me ? Do we assume that is a triangle? Maybe it is a straight line? If it is a triangle, then S1 is sufficient because the other side needs to less than ten. Thank you

The answer is E because you can't assume that it has to be a triangle. A, B and C can lay on a straight line too.

ritula · **Posted:** Wed Mar 18, 2009 8:11 am

oh yes....i didnt think of dat option. thanks!

jallenmorris wrote:

You're right if you think of it as a triangle, but a triangle is not the only option. The points are on a plane, and the points COULD be in a line and still on the same plane. If this happens, and say the points go A-C-B, then the distance between AB would be 10, not less than 10, so 1 is insufficient.

ritula wrote:

A, B , and C are points on the plane. Is AB<10 ?

1. AC+BC=10
2. AB+AC>10

Shldnt 1 be sufficient ?
bcos if we make a triangle of these three points then triangle property says "The sum of the lengths of any two sides of a triangle must be greater than the third side" then AC+BC>AB
since AB+BC=10 Hence AB<10

bipolarbear · **Posted:** Thu Jul 30, 2009 7:57 am

This question is so tricky! Gmat test takers can't be THAT cunning that can they!? :roll:

tssambi · **Posted:** Fri Sep 09, 2011 5:37 am

Yes answer should be E. Here is my explanation -

Stmt1: AC+BC = 10
Try to plot three points on a sheet of paper.You can either have a triangle or a line.
- If you plot a triangle, it is clear that AB<10 (sum of any two sides will always be more than the third side).
- If you plot a line using three points, and given that AC+BC = 10, we can conclude that C lies between A and B on the line. In other words, AC+BC=AB=10.
So, in one case you get AB<10 and in other case you get AB=10. Thus INSUFFICIENT.

Stmt2: AB+AC > 10 (10.1 or 20, it doesnt matter. Both are greater than 10)
1+10 > 10 (AB=1, and is thus <10)
10+10 > 10 (AB=10 and is equal to 10)
2 values, thus INSUFFICIENT.

Lets combine the two statements now.

From stmt1, we have AC=10-BC. Put this is stmt2. That is AB + 10 - BC >10.
We also know from stmt1 that AB can be either <10 or =10. You can now put AB=10 and AB=9 in equation above to see that both can be valid. Thus together the two statements are INSUFFICIENT. Hence, E.

PLease be generous in giving kudos incase you liked the explanation

lexis · **Posted:** Fri Jul 18, 2008 3:29 am

A.
Sum of two sides of triangle is always greater than the rest.

bhushangiri · **Posted:** Fri Jul 18, 2008 4:39 am

IMO the answer is E. Neither equation nor the inequality tells u if the 3 points are collinear or vertices of triangle. So nothing can be inferrd.

alpha_plus_gamma · **Posted:** Fri Jul 18, 2008 7:01 am

sset009 wrote:

but how do u know its a triangle?
and not on a straight line?

E should be the answer, you are correct.

FN · **Posted:** Fri Jul 18, 2008 7:33 am

i have fallen for such mistakes before..now its etched into memory..

you dont know if the points are in a triangular coordinates..

E is best..

dczuchta · **Posted:** Mon Sep 29, 2008 4:25 pm

A ,B , and C and are points on the plane. Is AB<10 ?

1) AC+BC=10
2) AB+AC >10

Answer: E

Can someone pls explain this DS answer to me ? Do we assume that is a triangle? Maybe it is a straight line? If it is a triangle, then S1 is sufficient because the other side needs to less than ten. Thank you

ritula · **Posted:** Wed Mar 18, 2009 2:49 am

A, B , and C are points on the plane. Is AB<10 ?

1. AC+BC=10
2. AB+AC>10

Shldnt 1 be sufficient ?
bcos if we make a triangle of these three points then triangle property says "The sum of the lengths of any two sides of a triangle must be greater than the third side" then AC+BC>AB
since AB+BC=10 Hence AB<10

jallenmorris · **Posted:** Wed Mar 18, 2009 4:01 am

You're right if you think of it as a triangle, but a triangle is not the only option. The points are on a plane, and the points COULD be in a line and still on the same plane. If this happens, and say the points go A-C-B, then the distance between AB would be 10, not less than 10, so 1 is insufficient.

ritula wrote:

A, B , and C are points on the plane. Is AB<10 ?

1. AC+BC=10
2. AB+AC>10

Shldnt 1 be sufficient ?
bcos if we make a triangle of these three points then triangle property says "The sum of the lengths of any two sides of a triangle must be greater than the third side" then AC+BC>AB
since AB+BC=10 Hence AB<10

Economist · **Posted:** Thu Mar 26, 2009 5:58 am

So the answer is E right?

ritula · **Posted:** Thu Mar 26, 2009 8:44 am

yes OA is E

Economist wrote:

So the answer is E right?

ankur17 · **Posted:** Sat Jul 24, 2010 8:53 pm

sset009 wrote:

but how do u know its a triangle?
and not on a straight line?

damn it .. got tricked again :wall

matt3030 · **Posted:** Sat Jul 31, 2010 12:05 pm

Interesting. I assume that if the question prompt was something like "A, B and C are distinct points on a plane" that the answer would be (a)?

srivicool · **Posted:** Mon Sep 06, 2010 5:28 am

tricky one... hope this is 700+level question...

varun2410 · **Posted:** Mon Sep 06, 2010 9:24 pm

IMO E we can conclude S1 is suff. if it was given that points are not in line

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m9 q34

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