Each person attending a fund-raising party for a certain clu : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 24 Jan 2017, 12:13

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Each person attending a fund-raising party for a certain clu

Author Message
TAGS:

### Hide Tags

SVP
Joined: 21 Jul 2006
Posts: 1538
Followers: 10

Kudos [?]: 744 [2] , given: 1

Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

11 Dec 2007, 14:48
2
KUDOS
6
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

70% (01:52) correct 30% (00:58) wrong based on 191 sessions

### HideShow timer Statistics

Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?

(1) If the admission fee had been 0.75$less and 100 more people had attended, the club would have received the same amount in admission fee (2) If the admission fee had been 1.50$ less and 100 fewer people had attended, the club would have received the same amount in admission fee

OPEN DISCUSSION OF THIS QUESTION IS HERE: each-person-attending-a-fund-raising-party-for-a-certain-clu-101572.html
[Reveal] Spoiler: OA
Director
Joined: 12 Jul 2007
Posts: 862
Followers: 15

Kudos [?]: 286 [0], given: 0

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

11 Dec 2007, 14:55
wow...this one is deceptively tricky for me. I'm not sure anymore
Intern
Joined: 13 Jun 2007
Posts: 48
Followers: 1

Kudos [?]: 8 [0], given: 0

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

11 Dec 2007, 15:30
P- original number of people

1) AP=(A-0.75)(P+100)
AP=AP+100A-0.75P -75
0=100A-0.75P-75
1 equation, 2 unknowns

2) AP=(A+1.5)(P-100)
AP=AP-100A+1.5P-150
0=-100A+1.5P-150
1 equation, 2 unknowns

1) + 2) 0=0+0.75P-225=> P=225*4/3=300
SVP
Joined: 21 Jul 2006
Posts: 1538
Followers: 10

Kudos [?]: 744 [0], given: 1

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

14 Dec 2007, 10:51
the OA is C. Anyone else wanna try this?
CIO
Joined: 09 Mar 2003
Posts: 463
Followers: 2

Kudos [?]: 58 [1] , given: 0

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

14 Dec 2007, 11:06
1
KUDOS
3
This post was
BOOKMARKED
alexperi wrote:
P- original number of people

1) AP=(A-0.75)(P+100)
AP=AP+100A-0.75P -75
0=100A-0.75P-75
1 equation, 2 unknowns

2) AP=(A+1.5)(P-100)
AP=AP-100A+1.5P-150
0=-100A+1.5P-150
1 equation, 2 unknowns

1) + 2) 0=0+0.75P-225=> P=225*4/3=300

I completely agree with this, but it's a little too much. The moment you have the first equation, you should know you can't solve, and the same with the second one. Together, you've got two equations and two variables, so you should be able to solve.

The only risk here is that sometimes, with two equations, you can't solve. But if you learn the times when you can't, you can do a quick check for them and move on. They are:

1) When the equations are the same but look different
Example:
y = 3x + 6
6x = 2y - 12
These are actually the same equation.

2) When there are powers in one or both equation
Example:
y^2 + x = 9
x + 2y = 6

3) When one of the variables actually disappears, and you should have picked A or B
Example:
3x + 2y = 18
x + y = 4x + y + 12 <-- the y's cancel here so there's actually only 1 variable.

So look at the two equations and make sure quickly that you're not in any of those three situations (a very fast test when you get used to looking for them) and then the answer is C right away.
Director
Joined: 03 May 2007
Posts: 886
Schools: University of Chicago, Wharton School
Followers: 6

Kudos [?]: 190 [0], given: 7

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

14 Dec 2007, 11:27
2
This post was
BOOKMARKED
tarek99 wrote:
Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?

(1) If the admission fee had been $0.75 less and 100 more people had attended, the club would have received the same amount in admission fees. (2) If the admission fee had been$1.50 more and 100 fewer people had attended, the club would have received the same amount in admission fees.

C.
1: xy = (x-0.75) (y+100)
100x -0.75y = 75
100x = 0.75y + 75

2: xy = (x+1.50) (y-100)
xy = xy - 100x + 1.50y - 150
1.50y - 100x = 150
1.50y - 150 = 100x

togather, solve for 1 and 2:

0.75y + 75 = 1.50y - 150
0.75y = 225
y = 300
x = 2.25
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13546
Followers: 578

Kudos [?]: 163 [0], given: 0

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

11 Aug 2014, 17:19
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.
_________________
Manager
Joined: 22 Feb 2009
Posts: 229
Followers: 5

Kudos [?]: 133 [0], given: 148

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

11 Aug 2014, 20:44
tarek99 wrote:
Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?

(1) If the admission fee had been $0.75 less and 100 more people had attended, the club would have received the same amount in admission fees. (2) If the admission fee had been$1.50 more and 100 fewer people had attended, the club would have received the same amount in admission fees.

C is also my answer. If someone thinks D is answer, could you please give an explanation?
_________________

.........................................................................
+1 Kudos please, if you like my post

Math Expert
Joined: 02 Sep 2009
Posts: 36638
Followers: 7106

Kudos [?]: 93658 [0], given: 10583

Re: Each person attending a fund-raising party for a certain clu [#permalink]

### Show Tags

12 Aug 2014, 07:37
tarek99 wrote:
Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?

(1) If the admission fee had been 0.75$less and 100 more people had attended, the club would have received the same amount in admission fee (2) If the admission fee had been 1.50$ less and 100 fewer people had attended, the club would have received the same amount in admission fee

OPEN DISCUSSION OF THIS QUESTION IS HERE: each-person-attending-a-fund-raising-party-for-a-certain-clu-101572.html
_________________
Re: Each person attending a fund-raising party for a certain clu   [#permalink] 12 Aug 2014, 07:37
Similar topics Replies Last post
Similar
Topics:
10 2/3 of all the people who attended a certain party arrived by 8:00 PM. 2 10 Nov 2015, 11:00
5 Each person in a certain group supports only one of two cand 8 23 Oct 2013, 04:47
1 Each person who attended a certain concert paid the same 11 02 Jun 2011, 18:35
11 Each person attending a fund-raising party for a certain club was 16 23 Sep 2010, 11:15
Each person attending a fund raising party for a certain 2 10 Jul 2010, 00:25
Display posts from previous: Sort by