corridor has four doors

Expert replies

sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Sat Jul 24, 2010 4:16 am

A certain straight corridor has four doors, A, B, C and D (in that order) leading off from the same side. How far apart are doors B and C?

1. The distance between doors B and D is 10 meters.
2. The distance between A and C is 12 meters.

[spoiler]Source: majortests.com[/spoiler]

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

Like this post

Source: Beat The GMAT — Data Sufficiency | Sat Jul 24, 2010 4:16 am

grockit_andrea: GMAT Instructor; Posts: 357; Joined: Wed Aug 12, 2009 8:31 pmFollowed by: 7 members; Thanked: 128 times

by grockit_andrea » Sat Jul 24, 2010 5:50 am

sanju09 wrote:A certain straight corridor has four doors, A, B, C and D (in that order) leading off from the same side. How far apart are doors B and C?

1. The distance between doors B and D is 10 meters.
2. The distance between A and C is 12 meters.

[spoiler]Source: majortests.com[/spoiler]

Statement 1 alone is insufficient, since we have no idea where C is located between B and D; it could be one foot from B and 9 feet from D, or right in the middle, or anywhere else. Eliminate A and D.

Statement 2 alone is again insufficient, since we have no idea where B is located between A and C. Eliminate B.

Now, take them together. We could sketch it like this:

10
--------B--------------------D
A------------------C
12

But we still don't know how long the entire corridor is, so the distances could vary:

10
----B--------------------D
A------------------C
12

10
------------------B--------------------D
A------------------C
12

And so on. Therefore, even taken together, Statements 1 and 2 are insufficient. The correct answer is E.

Andrea A.
Grockit Tutor
https://www.grockit.com

Like this post

sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Sat Jul 24, 2010 6:03 am

sanju09 wrote:A certain straight corridor has four doors, A, B, C and D (in that order) leading off from the same side. How far apart are doors B and C?

1. The distance between doors B and D is 10 meters.
2. The distance between A and C is 12 meters.

[spoiler]Source: majortests.com[/spoiler]

The phrase in bold matters

It's like A x B y C z D, where x, y, z being distances between the flanking doors. What is y?

1. y + z = 10. Insufficient
2. x + y = 12. Insufficient

Together, Just two equations in 3 variables, [spoiler]impossible!!

E[/spoiler]

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

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review