It is currently 16 Oct 2017, 17:49

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

In certain city, a car is parking at A destination, it will go to B de

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
1 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 41875

Kudos [?]: 128459 [1], given: 12173

In certain city, a car is parking at A destination, it will go to B de [#permalink]

Show Tags

New post 06 Oct 2017, 00:12
1
This post received
KUDOS
Expert's post
4
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

43% (01:11) correct 57% (00:31) wrong based on 21 sessions

HideShow timer Statistics

CHALLENGE QUESTIONS



In certain city, a car is parking at A destination, it will go to B destination along routes that are confined to square grid of x streets and y avenues, where streets and avenues are perpendicular to each other. How many routes from A to B can the car take that have the minimum possible length?

A. \(\frac{(x+y)!}{x!y!}\)

B. \(\frac{(x+y)!}{(x-1)!(y-1)!}\)

C. \(\frac{(x+y-1)!}{x!y!}\)

D. \(\frac{(x+y-2)!}{x!y!}\)

E. \(\frac{(x+y-2)!}{(x-1)!(y-1)!}\)
[Reveal] Spoiler: OA

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 128459 [1], given: 12173

1 KUDOS received
Intern
Intern
avatar
B
Joined: 22 Dec 2016
Posts: 2

Kudos [?]: 1 [1], given: 2

Location: Kazakhstan
Concentration: Finance, General Management
WE: Analyst (Retail Banking)
Re: In certain city, a car is parking at A destination, it will go to B de [#permalink]

Show Tags

New post 06 Oct 2017, 05:06
1
This post received
KUDOS
Please correct me if i'm wrong:

This is our travel map:

A.......
.........
.........
.........
.......B

In order to get from A to B we need to pass X-1 blocks (streets) plus Y-1 blocks (avenues); -1 because we start from a certain street and avenue and should not count them.
On every crossroad we can walk either DOWN or RIGHT, so our travel route will be something like DDDRDRDR, where D=X-1 times and R=Y-1 times.

We can do this in ((X-1)+(Y-1))!=(X+Y-2)! / (X-1)!(Y-1)! ways, so E?

Kudos [?]: 1 [1], given: 2

Expert Post
1 KUDOS received
Math Forum Moderator
avatar
P
Joined: 02 Aug 2009
Posts: 4961

Kudos [?]: 5447 [1], given: 112

Re: In certain city, a car is parking at A destination, it will go to B de [#permalink]

Show Tags

New post 07 Oct 2017, 06:32
1
This post received
KUDOS
Expert's post
Bunuel wrote:

CHALLENGE QUESTIONS



In certain city, a car is parking at A destination, it will go to B destination along routes that are confined to square grid of x streets and y avenues, where streets and avenues are perpendicular to each other. How many routes from A to B can the car take that have the minimum possible length?

A. \(\frac{(x+y)!}{x!y!}\)

B. \(\frac{(x+y)!}{(x-1)!(y-1)!}\)

C. \(\frac{(x+y-1)!}{x!y!}\)

D. \(\frac{(x+y-2)!}{x!y!}\)

E. \(\frac{(x+y-2)!}{(x-1)!(y-1)!}\)



hi..

apart from method above a QUICK solution may be..

take the simplest set of numbers - 2 streets and 2 avenues

so
12
34

ways 1-2-4 and 1-3-4, that is TWO ways

lets check choices for ans 2 when x and y are 2 each

A. \(\frac{(x+y)!}{x!y!}............\frac{(2+2)!}{2!2!}=6\)...NO

B. \(\frac{(x+y)!}{(x-1)!(y-1)!}..........\frac{4!}{1!1!}\)....NO

C. \(\frac{(x+y-1)!}{x!y!}......\frac{(2+2-1)!}{2!2!}=\frac{3}{2}.\)....NO

D. \(\frac{(x+y-2)!}{x!y!}...........\frac{(2+2-2)!}{2!2!}=\frac{1}{2}\)......NO

E. \(\frac{(x+y-2)!}{(x-1)!(y-1)!}..............\frac{(2+2-2)!}{1!1!}=2\)....YES and our answer

E
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

Kudos [?]: 5447 [1], given: 112

Re: In certain city, a car is parking at A destination, it will go to B de   [#permalink] 07 Oct 2017, 06:32
Display posts from previous: Sort by

In certain city, a car is parking at A destination, it will go to B de

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.