GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 23 Jan 2020, 21:29

### 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

# Among a group of 2,500 people, 35 percent invest in

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 60627
Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

14 Jun 2012, 02:49
10
54
00:00

Difficulty:

15% (low)

Question Stats:

81% (02:15) correct 19% (02:40) wrong based on 2697 sessions

### HideShow timer Statistics

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50

Diagnostic Test
Question: 4
Page: 20
Difficulty: 650

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 60627
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

14 Jun 2012, 02:49
13
9
SOLUTION

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50

Given:
$$0.35*2,500=875$$ invest in municipal bonds;
$$0.07*2,500=175$$ invest in in both municipal bonds and oil stocks;

Therefore $$875-175=700$$ invest in municipal bonds but NOT in in oil stocks. (Or directly: 35%-7%=28% of 2,500, which is 700, invest in municipal bonds but NOT in in oil stocks).

$$P=\frac{Favorable}{Total}=\frac{700}{2,500}=\frac{7}{25}$$.

_________________
Current Student
Joined: 29 Mar 2012
Posts: 295
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

Updated on: 09 Jul 2012, 01:04
13
5
Quote:
Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50
Hi,

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks.

As per the attached venn diagram, we have to find the number of people in shaded portion.
=35%-7%=28%

Thus, probability = 0.28 = 7/25

(2,500 people, 18 percent invest in oil stocks is not required.)

Attachments

m.jpg [ 9.55 KiB | Viewed 58057 times ]

Originally posted by cyberjadugar on 14 Jun 2012, 06:09.
Last edited by cyberjadugar on 09 Jul 2012, 01:04, edited 1 time in total.
##### General Discussion
Manager
Joined: 02 Jun 2011
Posts: 111
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

14 Jun 2012, 06:50
People with Municipal Bond but not with Oil Stock
= People with Municipal Bond and Oil stock – People with Municipal Bond but not Oil S
= 35%of 2500 – 7% of 2500
= 700
Now,
P ( one person investing in Municipal Bond but not in Oil Stock ) = 700 /2500 = 7/25

Intern
Joined: 03 Jun 2012
Posts: 24
Location: United States
WE: Project Management (Computer Software)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

14 Jun 2012, 20:19
1
1
Percentage investing in Municipal bonds = 35%
Percentage investing in both = 7%
Percentage investing in ONLY Municipal bonds = (35-7)% = 28%

Therefore, Probability of selecting one who invests Only in Municipal bonds = 28% = 28/100 = 7/25.
Manager
Joined: 07 Sep 2011
Posts: 59
Location: United States
GMAT 1: 640 Q39 V38
WE: General Management (Real Estate)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

16 Jun 2012, 03:52
Difficulty level 600+.

Probability of percentage invested in MB/ Total

35%-7%=28% of 2500= 700

P= 700/2500= 7/25
Director
Joined: 22 Mar 2011
Posts: 583
WE: Science (Education)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

Updated on: 18 Jun 2012, 08:14
10
2
For this type of question, I sometimes use a 2X2 table approach. The table is just an organized summary of the Venn diagram.
Since in this case a probability is required, there is no need to calculate actual numbers. So, using percentages, we can fill out the table (see attached image). I started with 35, 18 and 7, then for example 11=18-7, 28=35-7, 82=100-18, 54=82-28, 65=100-35. There is more than one possible sequence. Necessarily, one must get the sum in the bottom row and that in the rightmost column exactly 100.
In fact, you don't need to fill out the whole table, once you have that Municipal and noOil represents 28%, you are done. I present the whole table just to illustrate the use of it.

So, those who invest in Municipal and noOil stocks represent 28%=28/100=7/25.

Correct asnwer is B.
Attachments

OG13-Diagn-4.jpg [ 36.89 KiB | Viewed 57744 times ]

_________________
PhD in Applied Mathematics
Love GMAT Quant questions and running.

Originally posted by EvaJager on 18 Jun 2012, 07:07.
Last edited by EvaJager on 18 Jun 2012, 08:14, edited 1 time in total.
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 10011
Location: Pune, India

### Show Tags

11 Jun 2015, 20:43
4
1
LouieV wrote:
Hello everyone and thank you for this forum!!!

I admit it has been a few years since I've sat down to attack standardized test, but my GOODNESS ! Can someone please lend some wisdom on this problem from TOG 2016 pg 20 #4.

Among a group of 2500 people, 35% invest in municipal bonds, 18% invest in oil stocks, and 7% invest in both municipal bonds and oil stocks. If 1 person is randomly selected from the 2500 people, what is the probability that the person will be one who invests in municipal bonds but NOT in oil stocks?

A. 9/50
B. 7/25
C. 7/20
D. 21/50
E. 27/50

So this question actually pertains to overlapping sets.

Say, there are 100 people instead (since we have percentages)
Number of people investing in MB = 35
Number of people investing in OS = 18
Number of people investing in both = 7

So how many people invest in MB but not OS? 35 invest in MB but 7 invest in both (so out of 35, 7 invest in OC too). We need to remove these 7 since we need the number of people who invest in MB only. We get 28.
So 28 out of 100 people invest in only MB. So out of 100, if we pick one person, the probability that he invests in MB only is 28/100 = 7/25

The probability remains same no matter how many people there are - 100 or 2500 or 500000 etc.

Check out overlapping sets: http://www.veritasprep.com/blog/2012/09 ... ping-sets/
_________________
Karishma
Veritas Prep GMAT Instructor

CEO
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 3026
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)

### Show Tags

11 Jun 2015, 20:49
2
LouieV wrote:
Hello everyone and thank you for this forum!!!

I admit it has been a few years since I've sat down to attack standardized test, but my GOODNESS ! Can someone please lend some wisdom on this problem from TOG 2016 pg 20 #4.

Among a group of 2500 people, 35% invest in municipal bonds, 18% invest in oil stocks, and 7% invest in both municipal bonds and oil stocks. If 1 person is randomly selected from the 2500 people, what is the probability that the person will be one who invests in municipal bonds but NOT in oil stocks?

A. 9/50
B. 7/25
C. 7/20
D. 21/50
E. 27/50

Total People = 2500 people

35% invest in municipal bonds, i.e Probability of Investing in Mutual Bonds = 0.35
i.e. i.e Probability of NOT Investing in Mutual Bonds = 0.65

18% invest in oil stocks i.e Probability of Investing in Oil stock = 0.18
i.e Probability of NOT Investing in Oil stock = 0.82

7% invest in both municipal bonds and oil stocks = 0.07

i.e. we can conclude that Probability of NOT investing in any one of them = 1-(0.35+0.18+0.07) = 0.54

Probability of Investing in Mulual Bond but NOT in Oil Stock = 0.82-0.54 = 0.28 = 28/100 = 7/25

Attachments

File comment: www.GMATinsight.com

113.jpg [ 73.99 KiB | Viewed 44536 times ]

_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Intern
Joined: 11 Jun 2015
Posts: 1

### Show Tags

11 Jun 2015, 21:46
Thank you for explaining this in such simple terms Karishma. GMATinsight, the visual was definitely a big help in allowing me to see the arithmetic behind the words. I was stomped, but I'm sure my gears will get back to speed as I progress in my preparation. THANKS EVERYONE!
Senior Manager
Joined: 10 Mar 2013
Posts: 459
Location: Germany
Concentration: Finance, Entrepreneurship
Schools: WHU MBA"20 (A\$)
GMAT 1: 580 Q46 V24
GPA: 3.88
WE: Information Technology (Consulting)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

04 Sep 2015, 01:59
The fastest way is from Bunuel, but in this case I would stay with percents, as it is easier to calculate: 35%-7%(overlap)=28% --> 28%/100%=7/25
Attachments

PS D4.JPG [ 19.36 KiB | Viewed 41007 times ]

Manager
Joined: 10 May 2014
Posts: 135
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

04 Sep 2015, 08:16
The piece of information that states that "there are 2,500 people" is completely irrelevant, right?
In other words you can yield the correct answer without that piece of data.
Manager
Joined: 01 Jun 2013
Posts: 100
GMAT 1: 650 Q50 V27
Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

07 Sep 2015, 11:53
No need to calculate number of people

Both OS and Muni: 7%, therefore, Muni only: 28% and OS only:11%

Muni Only / All = 28%/1 >> 7/25
Manager
Joined: 17 Mar 2014
Posts: 120
Location: United States
GPA: 3.97
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

08 Dec 2015, 09:29
Bunuel wrote:
Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50

Diagnostic Test
Question: 4
Page: 20
Difficulty: 650

For this Q - I was thinking why cant we assume that "35%" mentioned only include people that invest in municipal bonds. But Karishma from Veriats cleared the doubt. ONLY should have been mentioned - if that was the case. Below excerpts of her reply -
"Yes, if they say, "35% invest in municipal bonds only and 7% invest in both," then the two are mutually exclusive."
Intern
Joined: 01 Aug 2015
Posts: 1
Schools: Wharton '19
GMAT 1: 720 Q49 V41
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

17 Jan 2016, 07:44
Question - why isn't it 0.35 * 0.82 (the number of people who don't invest in oil) ?

Thanks much.
CEO
Joined: 20 Mar 2014
Posts: 2548
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

17 Jan 2016, 08:08
1
nellietyf wrote:
Question - why isn't it 0.35 * 0.82 (the number of people who don't invest in oil) ?

Thanks much.

Because those 82% people also include people who do not go for either the municipal bonds or the stocks. Refer to the attached figure.

Text in red : calculated, text in black: calculated.

Attachment:

2016-01-17_10-07-18.jpg [ 22.63 KiB | Viewed 25198 times ]

Thus the required probability =700/2500 = 7/25.

B is thus the correct answer.

Hope this helps.
Intern
Joined: 13 Oct 2011
Posts: 4
Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

20 Sep 2016, 13:48
Why didn't we say: P( bonds only) & P(not oil), which is P(bonds only) & P(1- p(oil))??
Isn't it the translation of NOT oil?

This is contradicting with solution of this OG PS question:

215- Xavier, Yvonne, and Zelda each try independently to solve a problem. If their individual probabilities for success are 1/4, 1/2 and 5/8, respectively, what is the probability that Xavier and Yvonne, but not Zelda, will solve the problem?

The solution considered the p(not zelda)!
I am confused.
Manager
Joined: 07 Jun 2017
Posts: 159
Location: India
Concentration: Technology, General Management
GMAT 1: 660 Q46 V38
GPA: 3.6
WE: Information Technology (Computer Software)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

11 Dec 2017, 23:23
People with Municipal Bond and Oil stock – People with Municipal Bond but not Oil S
= 35%of 2500 – 7% of 2500
= 700
700 /2500 = 7/25 Answer B
VP
Joined: 09 Mar 2016
Posts: 1223
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

25 Feb 2018, 04:45
Bunuel wrote:
SOLUTION

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50

Given:
$$0.35*2,500=875$$ invest in municipal bonds;
$$0.07*2,500=175$$ invest in in both municipal bonds and oil stocks;

Therefore $$875-175=700$$ invest in municipal bonds but NOT in in oil stocks. (Or directly: 35%-7%=28% of 2,500, which is 700, invest in municipal bonds but NOT in in oil stocks).

$$P=\frac{Favorable}{Total}=\frac{700}{2,500}=\frac{7}{25}$$.

Bunuel is there a shortcut to calculate percent when it comes to big numbers. Quote time consuming....

$$0.35*2,500=875$$ invest in municipal bonds;
$$0.07*2,500=175$$ invest in in both municipal bonds and oil stocks;
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 9125
Location: United States (CA)
Re: Among a group of 2,500 people, 35 percent invest in  [#permalink]

### Show Tags

12 Apr 2018, 16:29
Bunuel wrote:
Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds but NOT in oil stocks?

(A) 9/50
(B) 7/25
(C) 7/20
(D) 21/50
(E) 27/50

The number of people who invest in ONLY municipal bonds is:

2,500 x 0.35 - 2,500 x 0.07

2,500(0.35 - 0.07) = 2,500(0.28) = 700

So, the probability that the person selected will be one who invests in municipal bonds and NOT in oil stocks is 700/2500 = 7/25.

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
181 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Re: Among a group of 2,500 people, 35 percent invest in   [#permalink] 12 Apr 2018, 16:29

Go to page    1   2    Next  [ 22 posts ]

Display posts from previous: Sort by