Kaplan tough one

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arora007: Community Manager; Posts: 1048; Joined: Mon Aug 17, 2009 3:26 am; Location: India; Thanked: 51 times; Followed by:27 members; GMAT Score:670

Kaplan tough one

by arora007 » Sun Aug 15, 2010 2:03 am

If, on a co-ordinate plane point A has the co-ordinates (-3,4) how fare is point A from point E ?

a) point E is on the y axis 4 units from the origin.

b) If point A were taken twice as far from point E, it would be the same distance from point E as point C is at co-ordinates(0,-2)

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Source: Beat The GMAT — Data Sufficiency | Sun Aug 15, 2010 2:03 am

ankurmit: Legendary Member; Posts: 516; Joined: Mon Nov 02, 2009 6:42 am; Location: Mumbai; Thanked: 14 times; Followed by:1 members; GMAT Score:710

by ankurmit » Sun Aug 15, 2010 2:43 am

Stem 1 will give us answers as 3 or (73)^1/2

Stem 2 will give us answer as (45)^1/2 / (2)

Its a tough one.

I think answere should be B ..

Please post OA by today as I have my GMAT test tomorrow

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Ankur mittal

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

by Ian Stewart » Sun Aug 15, 2010 3:07 am

arora007 wrote:If, on a co-ordinate plane point A has the co-ordinates (-3,4) how fare is point A from point E ?

a) point E is on the y axis 4 units from the origin.

b) If point A were taken twice as far from point E, it would be the same distance from point E as point C is at co-ordinates(0,-2)

From Statement 1, there are two possible locations for point E, at (0,4) and at (0,-4), and since the distance from A to E will be different in each case, Statement 1 is not sufficient.

Statement 2 is also not sufficient; it just tells us that the distance AE is half of the distance CE. We might imagine connecting points A and C. There will be a point on that line which is twice as far from C as from A (the point is at (-2, 2)). This will give us the closest possible point to A; the distance AE is then sqrt(5). But, as the first statement might help us to see, Point E might be at (0,4), in which case the distance AE is 3, among other possibilities.

Combined, the only way both statements can be true is if E is at (0,4), so the answer is C.

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ankurmit: Legendary Member; Posts: 516; Joined: Mon Nov 02, 2009 6:42 am; Location: Mumbai; Thanked: 14 times; Followed by:1 members; GMAT Score:710

by ankurmit » Sun Aug 15, 2010 3:42 am

Thanks Ian...

I may be wrong but

Cordinates of point C are given as (0,-2) and this point will lie on Y-axis only .....please consider this

Using this I think answer will be B

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Ankur mittal

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arora007: Community Manager; Posts: 1048; Joined: Mon Aug 17, 2009 3:26 am; Location: India; Thanked: 51 times; Followed by:27 members; GMAT Score:670

by arora007 » Sun Aug 15, 2010 5:16 am

OA C, this one was among the 3 wrong I got on the kaplan test... and resulted in a 50

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ankurmit: Legendary Member; Posts: 516; Joined: Mon Nov 02, 2009 6:42 am; Location: Mumbai; Thanked: 14 times; Followed by:1 members; GMAT Score:710

by ankurmit » Sun Aug 15, 2010 5:23 am

Can u please post explanation for 2nd stem..

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Ankur mittal

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 am; Location: Montreal; Thanked: 1090 times; Followed by:355 members; GMAT Score:780

by Ian Stewart » Sun Aug 15, 2010 10:24 am

ankurmit wrote:

Cordinates of point C are given as (0,-2) and this point will lie on Y-axis only .....please consider this

Yes, the coordinates of point C are given, as are the coordinates of point A. The coordinates of point E, however, are not given, and since we are measuring the distances AE and CE, we need some information about the location of E.

I think it's quite easy to misinterpret Statement 2. Statement 2 does *not* tell you that the length of AC is twice the length of AE. If it told you that, it would certainly be sufficient, since we could find the length of AC using the given coordinates.

For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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