NEW HERE? LEARN MORE
closeclose
Last visit was: 23 Apr 2024, 14:02 It is currently 23 Apr 2024, 14:02
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

In a certain conference room each row of chairs has the same number of

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
enigma123
Senior Manager
Senior Manager
Joined: 25 Jun 2011
Status:Finally Done. Admitted in Kellogg for 2015 intake
Posts: 396
Own Kudos [?]: 16643 [96]
Given Kudos: 217
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE:Information Technology (Consulting)
Send PM
In a certain conference room each row of chairs has the same number of [#permalink] New post   20 Mar 2012, 10:30
8
Kudos
88
Bookmarks
00:00
A
B
C
D
E

Difficulty:

25% (medium)

Question Stats:

76% (01:34) correct 24% (01:48) wrong based on 1149 sessions
Hide Show timer Statistics
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

(1) There is a total of 72 chairs.
(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows.
ShowHide Answer
Official Answer
D
Most Helpful Reply
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618584 [47]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   20 Mar 2012, 12:52
22
Kudos
25
Bookmarks
Expert Reply
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.

(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows --> C+(C-1)=17 --> C=9. Sufficient.

Answer: D.
User avatar
TeamGMATIFY
Tutor
Joined: 20 Aug 2015
Posts: 350
Own Kudos [?]: 1392 [5]
Given Kudos: 10
Location: India
GMAT 1: 760 Q50 V44
Send PM
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   16 Nov 2015, 00:35
3
Kudos
2
Bookmarks
Expert Reply
enigma123 wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

(1) There is a total of 72 chairs.
(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows.

Any idea how the answer would be D?


Given: Number of rows is 1 less than the number of chairs in a row and each row has same number of chairs.
Assuming the number of Chairs = C.
Number of rows = C-1

Required: C = ?

Statement 1: Total chairs = 72
Total chairs = (chairs in a row)*(number of rows) = C*(C-1)
C*(C-1) = 72, Hence C =9
SUFFICIENT

Statement 2: C + (C-1) =17
Hence C = 9
SUFFICIENT

Option D
General Discussion
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618584 [4]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   27 Dec 2015, 04:39
3
Kudos
1
Bookmarks
Expert Reply
redfield wrote:
Bunuel wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.


How do we calculate C(C-1)=72? Doesn't that become C^2-C =72? What is the next step there


There is an easier way. Since C must be a positive integer, then C(C-1) is the product of 2 consecutive integers. The product of 2 consecutive integers equal to 72 is 9*8.

Hope it helps.
avatar
S
redfield
Current Student
Joined: 18 Aug 2014
Posts: 303
Own Kudos [?]: 271 [2]
Given Kudos: 80
Send PM
GMAT ToolKit User Reviews Badge
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   26 Dec 2015, 15:57
2
Kudos
Bunuel wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.


How do we calculate C(C-1)=72? Doesn't that become C^2-C =72? What is the next step there
User avatar
G
anairamitch1804
Director
Director
Joined: 26 Oct 2016
Posts: 510
Own Kudos [?]: 3378 [1]
Given Kudos: 877
Location: United States
Concentration: Marketing, International Business
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE:Education (Education)
Send PM
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   12 Jan 2017, 18:24
1
Kudos
Let number of rows is a, number of the chairs in a row is b.
So, b-a=1
From 1, ab72, a8, b9, sufficient alone.
From 2, 2b-1=17, b=9, sufficient alone.
Answer is D.
User avatar
G
nkmungila
Manager
Manager
Joined: 07 Jun 2017
Posts: 116
Own Kudos [?]: 671 [1]
Given Kudos: 60
Location: India
Concentration: Technology, General Management
GMAT 1: 660 Q46 V38
GPA: 3.6
WE:Information Technology (Computer Software)
Send PM
GMAT ToolKit User Reviews Badge
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   06 Nov 2017, 22:02
1
Bookmarks
From A There is a total of 72 chairs. So it should be 9*8 Sufficient
From B After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows. last 2 total is enough to calculate So sufficient.
avatar
B
cman2010
Intern
Intern
Joined: 10 Sep 2017
Posts: 4
Own Kudos [?]: 1 [0]
Given Kudos: 6
Send PM
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   06 Nov 2017, 18:28
Bunuel wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.

(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows --> C+(C-1)=17 --> C=9. Sufficient.

Answer: D.



Where does "C(C-1)" come from? Why aren't you just plugging 72 into the equation C-1=R?
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618584 [0]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   06 Nov 2017, 21:57
Expert Reply
cman2010 wrote:
Bunuel wrote:
In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?

Say # of rows is R and # of chairs per row is C.
Given: R=C-1. Question: C=?

(1) There is a total of 72 chairs --> CR=72 --> C(C-1)=72 --> C=9. Sufficient.

(2) After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows --> C+(C-1)=17 --> C=9. Sufficient.

Answer: D.



Where does "C(C-1)" come from? Why aren't you just plugging 72 into the equation C-1=R?


We are told that the number of rows is 1 less than the number of chairs in a row. So, if the number of chairs per row is C, then the number of rows is C - 1 and thus the total number of chairs is (the number of chairs per row)*(the number of rows) = C(C-1).
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32627
Own Kudos [?]: 821 [0]
Given Kudos: 0
Send PM
Re: In a certain conference room each row of chairs has the same number of [#permalink] New post   08 Apr 2024, 10:19
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Bot
gmatclubot
Re: In a certain conference room each row of chairs has the same number of [#permalink]
08 Apr 2024, 10:19
Moderator:
Bunuel
Math Expert
92883 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions