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

It is currently 25 Jul 2014, 06:02

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

OG 11 PS #197

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
1 KUDOS received
Intern
Intern
avatar
Joined: 11 Apr 2008
Posts: 4
Followers: 0

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

OG 11 PS #197 [#permalink] New post 22 Apr 2008, 07:50
1
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (00:16) wrong based on 2 sessions
If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?

A. 10%
B. 20%
C. 30%
D. 50%
E. 65%

OA:E

I tried using the (group 1) + (group 2) - (neither) + (both) formula, but I seem that I cannot answer the question. What numbers do I need to plug in the above formula to receive E?
1 KUDOS received
SVP
SVP
User avatar
Joined: 24 Aug 2006
Posts: 2137
Followers: 3

Kudos [?]: 82 [1] , given: 0

GMAT Tests User
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 08:00
1
This post received
KUDOS
wwallace1 wrote:
If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?

A. 10%
B. 20%
C. 30%
D. 50%
E. 65%

OA:E

I tried using the (group 1) + (group 2) - (neither) + (both) formula, but I seem that I cannot answer the question. What numbers do I need to plug in the above formula to receive E?


Something doesn't seem right. If 65% answered both correctly, then how did only 55% answer the second question correctly.

Otherwise, it's D. 50% = both right, 25% = only A right, and 5% = only B right; finally 20% with none right.
Intern
Intern
avatar
Joined: 11 Apr 2008
Posts: 4
Followers: 0

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

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 08:17
Ah yes, sorry the answer is D.

How did you get 5% right for only B? when 55% answered the second question correctly?

I'm very confused how you solved this answer :(
1 KUDOS received
Director
Director
User avatar
Joined: 01 Jan 2008
Posts: 513
Followers: 3

Kudos [?]: 44 [1] , given: 0

GMAT Tests User Reviews Badge
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 08:31
1
This post received
KUDOS
wwallace1 wrote:
Ah yes, sorry the answer is D.

How did you get 5% right for only B? when 55% answered the second question correctly?

I'm very confused how you solved this answer :(


The answer is D. 75+55-80 :- 50 D
Intern
Intern
avatar
Joined: 11 Apr 2008
Posts: 4
Followers: 0

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

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 08:49
why are you subtracting by 80, i know .20 did not get either question right but what logic did you use to say that you needed to subtract by 80? (besides 100-20 = 80)
2 KUDOS received
Intern
Intern
User avatar
Joined: 07 Nov 2007
Posts: 27
Location: Dominican Republic
Followers: 0

Kudos [?]: 3 [2] , given: 0

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 09:46
2
This post received
KUDOS
I got this question in PowerPrep and the explanation had a graph... let me see if I can recall what it said.

...something like this.
Attachments

Untitled.jpg
Untitled.jpg [ 19.73 KiB | Viewed 1186 times ]

SVP
SVP
User avatar
Joined: 24 Aug 2006
Posts: 2137
Followers: 3

Kudos [?]: 82 [0], given: 0

GMAT Tests User
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 09:52
wwallace1 wrote:
amazing, Kudos! :D


Right. The formula is A + B - AB = 100

20% got neither correct, therefore --> A + B - AB = 80, plug and solve.
Director
Director
avatar
Joined: 05 Jan 2008
Posts: 709
Followers: 2

Kudos [?]: 86 [0], given: 0

GMAT Tests User
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 10:34
Got D , Good question and Good explanation
_________________

Persistence+Patience+Persistence+Patience=G...O...A...L

1 KUDOS received
Current Student
avatar
Joined: 28 Dec 2004
Posts: 3405
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 150 [1] , given: 2

GMAT Tests User
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 13:29
1
This post received
KUDOS
assume 100 people in class..

100-20= got some question correct

80=75+55-Both
Both=50
1 KUDOS received
Manager
Manager
avatar
Joined: 27 Mar 2008
Posts: 81
Followers: 1

Kudos [?]: 7 [1] , given: 0

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 14:52
1
This post received
KUDOS
o.o wrote:
I got this question in PowerPrep and the explanation had a graph... let me see if I can recall what it said.

...something like this.


How does C get calculated? I'm not understanding the Venn Diagram
SVP
SVP
User avatar
Joined: 24 Aug 2006
Posts: 2137
Followers: 3

Kudos [?]: 82 [0], given: 0

GMAT Tests User
Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 15:49
droopy57 wrote:
o.o wrote:
I got this question in PowerPrep and the explanation had a graph... let me see if I can recall what it said.

...something like this.


How does C get calculated? I'm not understanding the Venn Diagram


You just have to remember that A + B - C = The entire set. C = AB
Intern
Intern
User avatar
Joined: 07 Nov 2007
Posts: 27
Location: Dominican Republic
Followers: 0

Kudos [?]: 3 [0], given: 0

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 16:28
droopy57 wrote:
o.o wrote:
I got this question in PowerPrep and the explanation had a graph... let me see if I can recall what it said.

...something like this.


How does C get calculated? I'm not understanding the Venn Diagram

C is what we're being asked to look for, the number of people that got both questions right.

75% 1st question right
55% 2nd question right

Remember that the people that got both questions right are contained within those two percentages.

As said before, 75+55 = 130-80= 50.

50% represents the number of people that got both questions correct, so in fact only 5% of the grand total got only the 2nd question right and 25% got only the 1st one right.

Thus,
50+25+5+20=100
Manager
Manager
avatar
Joined: 27 Mar 2008
Posts: 81
Followers: 1

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

Re: OG 11 PS #197 [#permalink] New post 22 Apr 2008, 20:23
I found the Kaplan method... wwallace1 improperly set up the equation:

Total = Group 1 + Group 2 - Both + Neither

100 = 75 + 55 - x + 20

x = 50

I think this is a much easier approach, though I see how a Venn can visually aid.

Question for everyone:

How would you set up a chart diagram to solve this question? Column and Row set up
Manager
Manager
avatar
Joined: 05 Oct 2011
Posts: 169
GMAT 1: 720 Q V
Followers: 7

Kudos [?]: 34 [0], given: 60

GMAT ToolKit User GMAT Tests User Reviews Badge
Re: OG 11 PS #197 [#permalink] New post 03 Nov 2011, 11:29
Group1+Group2+Neither-Both=Total

75+55+20-B=100
150-100=B
b=50
Re: OG 11 PS #197   [#permalink] 03 Nov 2011, 11:29
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic PS OG11 #22 LM 4 09 Jan 2009, 21:07
OG 11 PS 229 pmenon 1 28 May 2008, 19:05
PS porblem OG-11 NevUR2Late? 6 09 Oct 2007, 05:10
OG11 PS Question lonesome307 1 09 Aug 2007, 14:13
PS - mileage (OG11) nick_sun 5 12 May 2007, 06:01
Display posts from previous: Sort by

OG 11 PS #197

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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

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®.