Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 06 May 2015, 03:48

### 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

# A marketing firm determined that, of 200 households

Author Message
TAGS:
SVP
Joined: 04 May 2006
Posts: 1936
Schools: CBS, Kellogg
Followers: 19

Kudos [?]: 442 [0], given: 1

A marketing firm determined that, of 200 households [#permalink]  28 Apr 2008, 17:14
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
A marketing firm determined that, of 200 households surveyed, 80 used neither Brand A nor Brand B soap, 60 usd only Brand A soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap?
A. 15
B. 20
C. 30
D. 40
E. 45

_________________
 Kaplan Promo Code Knewton GMAT Discount Codes Manhattan GMAT Discount Codes
Director
Joined: 10 Sep 2007
Posts: 949
Followers: 7

Kudos [?]: 206 [0], given: 0

Re: Set problem [#permalink]  28 Apr 2008, 17:55
Total Household = 200
Number of household who do not use any brands of soap = 80

Number of household who use any brands of soap = 200 - 80 = 120
Number of household who use brands A of soap = 60

Say x people used both brands, then 3*x = 3x people used only brand B.

As per Set theory
120 = 60 + 3x - x
=> 2x = 60
=> x = 30

Director
Joined: 10 Sep 2007
Posts: 949
Followers: 7

Kudos [?]: 206 [0], given: 0

Re: Set problem [#permalink]  28 Apr 2008, 18:30
Sorry got wrong calculation. Questions said "every household that used both brands of soap, 3 used only Brand B soap."

So if Say x people used both brands, then 3*x = 3x people used only brand B.
Then total number of people using brand B = 3x + x = 4x

So As per Set theory
120 = 60 + 4x - x
=> x = 20

Director
Joined: 20 Feb 2008
Posts: 797
Location: Texas
Schools: Kellogg Class of 2011
Followers: 6

Kudos [?]: 145 [0], given: 9

Re: Set problem [#permalink]  28 Apr 2008, 19:59
See attached
Attachments

untitled1.JPG [ 16.55 KiB | Viewed 823 times ]

SVP
Joined: 04 May 2006
Posts: 1936
Schools: CBS, Kellogg
Followers: 19

Kudos [?]: 442 [0], given: 1

Re: Set problem [#permalink]  28 Apr 2008, 20:12
abhijit_sen wrote:

Abhijit, thank for your support, but still be wrong!

jbpayne wrote:
See attached

thank jbpayne, but I am not a fan of diagram, it make me confused!

I like the equation:
Total = group A + group B - group (AB)...
and I am trying to set it up!
_________________
Director
Joined: 20 Feb 2008
Posts: 797
Location: Texas
Schools: Kellogg Class of 2011
Followers: 6

Kudos [?]: 145 [0], given: 9

Re: Set problem [#permalink]  28 Apr 2008, 20:53
The equation also works, but you need to know how to use the diagram as well. Try using the equation when you have three different groups instead of just two. It won't work nearly as easily as a picture.
Manager
Joined: 10 Mar 2008
Posts: 67
Followers: 2

Kudos [?]: 25 [0], given: 0

Re: Set problem [#permalink]  29 Apr 2008, 03:26
abhijit_sen wrote:
Sorry got wrong calculation. Questions said "every household that used both brands of soap, 3 used only Brand B soap."

So if Say x people used both brands, then 3*x = 3x people used only brand B.
Then total number of people using brand B = 3x + x = 4x

So As per Set theory
120 = 60 + 4x - x
=> x = 20

Hey Abhijit,
Brother u are close but u made a silly mistake
3x people used only brand B.
so it is
120=60(only A)+3x(Only B)+x(Both)
Ans is 15
Director
Joined: 10 Sep 2007
Posts: 949
Followers: 7

Kudos [?]: 206 [0], given: 0

Re: Set problem [#permalink]  29 Apr 2008, 13:24
Just a bad day. Getting couple of wrongs do not know why? May be over worked.
Formula still holds correctly. Rohit pointed out well. Cheers mate.
Re: Set problem   [#permalink] 29 Apr 2008, 13:24
Similar topics Replies Last post
Similar
Topics:
20 A marketing firm determined that, of 200 households surveyed 24 25 Jun 2012, 01:28
15 A marketing firm determined that, of 200 households 16 07 Jun 2008, 00:35
1 A marketing firm determined that, of 200 households 14 29 Dec 2007, 17:40
A marketing firm determined that, of 200 households 6 25 Dec 2005, 23:34
Display posts from previous: Sort by