BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

lying on the same

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

lying on the same

by sanju09 » Fri Feb 12, 2010 11:23 pm
If A, B, C and D are all points in the coordinate plane; then what is the ratio of the distance from B to C to the distance from C to D?

(1) The distance from A to C is twice the distance from C to D and three times the distance from B to D.

(2) The four points, A, B, C and D, all lie on a straight line.
Last edited by sanju09 on Tue Feb 16, 2010 2:06 am, edited 1 time in total.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Source: — Data Sufficiency |
Senior | Next Rank: 100 Posts
Posts: 87
Joined: Wed Jan 06, 2010 8:16 pm
Location: Chandigarh, INDIA

by onedayi'll » Sat Feb 13, 2010 12:37 pm
IMO E....

Let AC = 6; then CD = 3, with D on either side of C. BD=2, but B could be on either side of D,
we have no way of knowing length BC.
ratio BC/CD cannot be determined.
Gym/GMAT/Girl -- Be Serious
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Sat Feb 13, 2010 6:44 pm
sanju09 wrote:What is the value of the ratio BC/CD?

(1) AC = 2 CD = 3 BD.

(2) A, B, C, and D are the points lying on the same straight line.
This is an impossible question.

From (2), each letter represents a pair of coordinate points. From (1), each letter represents a single number. These two facts are contradictory.

While variables can certainly represent multiple things in the same question (e.g. we could have n workers who each get paid $n per hour), they cannot represent mutually exclusive concepts.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
User avatar
MBA Student
Posts: 403
Joined: Tue Dec 22, 2009 7:32 pm
Thanked: 98 times
Followed by:22 members

by fibbonnaci » Sun Feb 14, 2010 9:00 pm
Stuart, I do not understand why this is an impossible question.
2) gives the coordinate points, i agree. but 1) states the distances between those points.

what is wrong in that?
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Sun Feb 14, 2010 10:35 pm
fibbonnaci wrote:Stuart, I do not understand why this is an impossible question.
2) gives the coordinate points, i agree. but 1) states the distances between those points.

what is wrong in that?
I suppose that's one interpretation; but without statement (2), how do we know that they're points on the coordinate plane?

The common interpretation of (1) would be that a*c = 2*c*d = 3*b*d

On the actual GMAT, we never have to guess at what's going on - we're given all the information we need to interpret the question.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Legendary Member
Posts: 610
Joined: Fri Jan 15, 2010 12:33 am
Thanked: 47 times
Followed by:2 members

by kstv » Mon Feb 15, 2010 12:44 am
In the straight line AC = 2 CD = 3 BD. Then AC: CD: BD = 6: 3 : 2. Starting with AC which is 6 units, the point D can be (6-3) 3 units from A i.e in the order A D C in the st. line or (6+3) 9 units from A i.e. A C D. Similarly pt. B can be on either side of pt D at a distance of 2 units. Therefore the ratio can be 1/3 or 5/3.
Last edited by kstv on Mon Feb 15, 2010 8:06 am, edited 1 time in total.
Top
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

by sanju09 » Mon Feb 15, 2010 4:46 am
Stuart Kovinsky wrote:
sanju09 wrote:What is the value of the ratio BC/CD?

(1) AC = 2 CD = 3 BD.

(2) A, B, C, and D are the points lying on the same straight line.
This is an impossible question.

From (2), each letter represents a pair of coordinate points. From (1), each letter represents a single number. These two facts are contradictory.

While variables can certainly represent multiple things in the same question (e.g. we could have n workers who each get paid $n per hour), they cannot represent mutually exclusive concepts.
If I merely swap the statements, will it be fine then? It'll cost a single redo to me.
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 am
Thanked: 173 times
Followed by:2 members
GMAT Score:710

by gmatmachoman » Mon Feb 15, 2010 5:12 am
fibbonnaci wrote:Stuart, I do not understand why this is an impossible question.
2) gives the coordinate points, i agree. but 1) states the distances between those points.

what is wrong in that?
IMO C

I tried plugging in some random values :

CD= 3
---> BD= 2

CD+DB= 5= CB or BC

BC/CD=(5/3)

The straight line is formed by A,C,D,B points

Am i correct??
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Mon Feb 15, 2010 12:16 pm
sanju09 wrote: If I merely swap the statements, will it be fine then? It'll cost a single redo to me.
So is this a made-up question? Please always post the source!

Swapping the statements doesn't help, since the order is irrelevant; when we look at each statement individually, it needs to be able to exist in the absence of the other statement.

If fibbonnaci's interpretation is correct, then the question stem should read:
If A, B, C and D are all points in the coordinate plane, then what is the ratio of the distance from B to C to the distance from C to D?
and statement (1) should also be unambiguous:
(1) The distance from A to C is twice the distance from C to D and three times the distance from B to D.
finally, statement (2) should be slightly refined:
(2) A, B, C and D all lie on a straight line.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

by sanju09 » Tue Feb 16, 2010 2:07 am
Stuart Kovinsky wrote:
sanju09 wrote: If I merely swap the statements, will it be fine then? It'll cost a single redo to me.
So is this a made-up question? Please always post the source!

Swapping the statements doesn't help, since the order is irrelevant; when we look at each statement individually, it needs to be able to exist in the absence of the other statement.

If fibbonnaci's interpretation is correct, then the question stem should read:
If A, B, C and D are all points in the coordinate plane, then what is the ratio of the distance from B to C to the distance from C to D?
and statement (1) should also be unambiguous:
(1) The distance from A to C is twice the distance from C to D and three times the distance from B to D.
finally, statement (2) should be slightly refined:
(2) A, B, C and D all lie on a straight line.
Absolutely perfect. Thanks
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Post new topic Post Reply
• Page 1 of 1