Of the 50 guests at a party, 10 percent are smokers. How : GMAT Problem Solving (PS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 22 Jan 2017, 06:16

### 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

# Events & Promotions

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

# Of the 50 guests at a party, 10 percent are smokers. How

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

### Hide Tags

Manager
Joined: 25 Jul 2012
Posts: 78
Location: United States
Followers: 0

Kudos [?]: 89 [0], given: 137

Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

09 Aug 2012, 14:48
2
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

74% (01:39) correct 26% (01:18) wrong based on 182 sessions

### HideShow timer Statistics

Of the 50 guests at a party, 10 percent are smokers. How many non-smokers must leave in order to bring the number of smokers up to 50 percent of the guests?

A. 5
B. 10
C. 20
D. 35
E. 40

Kaplan's explanation:

Given 50 guests at a party, of whom 10% are smokers, how many nonsmokers would need to leave in order to have an equal number of smokers and nonsmokers?

Straight math is the best approach to this problem. If 10% of the 50 people are smokers, then there are 10% × 50 = 5 smokers and 50 – 5 = 45 nonsmokers. Smokers will represent 50% — or one-half — of the party guests when there are equal numbers of smokers and nonsmokers; that is, when there are 5 nonsmokers remaining. This means that 40 of the 45 nonsmokers must leave. Answer Choice (E) is correct.

Can someone please explain in a better way the logic to the answer of this problem? I got down:

50 guests @ party:
.10 ---> 5 are smokers
.90 ---> 45 are non smokers

I don't understand why 40 have to leave? It's probably easy but I don't see it.
[Reveal] Spoiler: OA

_________________

If my post has contributed to your learning or teaching in any way, feel free to hit the kudos button ^_^

 Kaplan GMAT Prep Discount Codes e-GMAT Discount Codes Veritas Prep GMAT Discount Codes
Math Expert
Joined: 02 Sep 2009
Posts: 36597
Followers: 7093

Kudos [?]: 93429 [1] , given: 10563

Re: Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

09 Aug 2012, 14:56
1
This post received
KUDOS
Expert's post
Of the 50 guests at a party, 10 percent are smokers. How many non-smokers must leave in order to bring the number of smokers up to 50 percent of the guests?

A. 5
B. 10
C. 20
D. 35
E. 40

Now, there are 5 smokers (10% of 50) and 50-5=45 non-smokers at a party. We need there to be 5 smokers and 5 non-smokers, in this case there will be 50% smokers and 50% non-smokers.

Therefore 45-5=40 non-smokers must leave.

Answer: E.
_________________
Manager
Joined: 25 Jul 2012
Posts: 78
Location: United States
Followers: 0

Kudos [?]: 89 [0], given: 137

Re: Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

10 Aug 2012, 07:31
Bunuel wrote:
[b]We need there to be 5 smokers and 5 non-smokers, in this case there will be 50% smokers and 50% non-smokers.

Therefore 45-5=40 non-smokers must leave.

Answer: E.

Ahh that makes sense, thanks much!
_________________

If my post has contributed to your learning or teaching in any way, feel free to hit the kudos button ^_^

Intern
Joined: 11 Jul 2012
Posts: 46
Followers: 0

Kudos [?]: 5 [0], given: 0

Re: Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

10 Nov 2012, 02:03
See it as a ratio problem. Let X be number of smokers and Y that of non-smokers (X = 5, Y = 45)
For X to be 50% of the total that mean X shld be = to new nber of Y (let that be Y-a). Thus
X/Y-a = 1 ==> 5= 45-a ==> a = 40
Brother Karamazov
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13499
Followers: 577

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

Re: Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

16 Jan 2015, 05:51
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.
_________________
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 8314
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Followers: 381

Kudos [?]: 2468 [0], given: 163

Re: Of the 50 guests at a party, 10 percent are smokers. How [#permalink]

### Show Tags

16 Jan 2015, 13:27
Hi All,

The math behind this question is pretty simple, as the other explanations have pointed out. If you can't see the "math" approach to this question, then you can use the ANSWERS to your advantage and "brute force" the solution.

We're told that 50 people are at a party and 10% of them are smokers:

Total = 50
Smokers = 5
Non-Smokers = 45

We're then asked how many smokers would need to leave the party to make it so the total party guests are 50% smokers. This means that we will SUBTRACT a number from 45.....since the answer choices are numbers, we can TEST THE ANSWERS until we get a match.

A: 5 --> remove 5 non-smokers....
Smokers = 5
Non-Smokers = 40
5/45 is NOT 50% smokers

B: 10 --> remove 10 non-smokers..
Smokers = 5
Non-Smokers = 35
5/40 is NOT 50% smokers

C:A: 20 --> remove 20 non-smokers....
Smokers = 5
Non-Smokers = 25
5/30 is NOT 50% smokers

D: 35 --> remove 35 non-smokers..
Smokers = 5
Non-Smokers = 10
5/15 is NOT 50% smokers

E: 40 --> remove 40 non-smokers..
Smokers = 5
Non-Smokers = 5
5/10 IS 50% smokers
This MUST be the answer.

Final Answer:
[Reveal] Spoiler:
E

GMAT assassins aren't born, they're made,
Rich
_________________

# Rich Cohen

Co-Founder & GMAT Assassin

# Special Offer: Save \$75 + GMAT Club Tests

60-point improvement guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Re: Of the 50 guests at a party, 10 percent are smokers. How   [#permalink] 16 Jan 2015, 13:27
Similar topics Replies Last post
Similar
Topics:
1 What Percent of 10 is 10 Percent of 1? 6 06 Nov 2016, 14:56
1 At a particular graduation party with 300 guests, 70% of the guests 2 06 Apr 2016, 00:42
2 At a dinner party, 40 percent of the guests wore both jackets and ties 4 06 Apr 2016, 00:15
13 How many gallons of milk that is 10 percent butter-fat must 10 03 Sep 2013, 05:35
1 30 people were invited to a dinner party. If 17 of the guest 13 09 Dec 2012, 02:34
Display posts from previous: Sort by

# Of the 50 guests at a party, 10 percent are smokers. How

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

 Powered by phpBB © phpBB Group and phpBB SEO 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®.