It is currently 19 Mar 2018, 07:43

### 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

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

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 44320
Among a group of 2,500 people, 35 percent invest in [#permalink]

### Show Tags

14 Jun 2012, 02:49
Expert's post
21
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

81% (01:46) correct 19% (02:12) wrong based on 1722 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
[Reveal] Spoiler: OA

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 44320
Re: Among a group of 2,500 people, 35 percent invest in [#permalink]

### Show Tags

14 Jun 2012, 02:49
12
KUDOS
Expert's post
6
This post was
BOOKMARKED
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: 319
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

14 Jun 2012, 06:09
6
KUDOS
2
This post was
BOOKMARKED
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 36642 times ]

Last edited by cyberjadugar on 09 Jul 2012, 01:04, edited 1 time in total.
Manager
Joined: 02 Jun 2011
Posts: 145
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: 30
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
KUDOS
1
This post was
BOOKMARKED
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: 62
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: 608
WE: Science (Education)
Re: Among a group of 2,500 people, 35 percent invest in [#permalink]

### Show Tags

18 Jun 2012, 07:07
6
KUDOS
1
This post was
BOOKMARKED
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 36404 times ]

_________________

PhD in Applied Mathematics
Love GMAT Quant questions and running.

Last edited by EvaJager on 18 Jun 2012, 08:14, edited 1 time in total.
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7992
Location: Pune, India

### Show Tags

11 Jun 2015, 20:43
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
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
My Blog

Get started with Veritas Prep GMAT On Demand for \$199

Veritas Prep Reviews

SVP
Joined: 08 Jul 2010
Posts: 2017
Location: India
GMAT: INSIGHT
WE: Education (Education)

### Show Tags

11 Jun 2015, 20:49
2
KUDOS
Expert's post
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

[Reveal] Spoiler:
B

Attachments

File comment: www.GMATinsight.com

113.jpg [ 73.99 KiB | Viewed 23234 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

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!
Director
Joined: 10 Mar 2013
Posts: 581
Location: Germany
Concentration: Finance, Entrepreneurship
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 19711 times ]

_________________

When you’re up, your friends know who you are. When you’re down, you know who your friends are.

800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50
GMAT PREP 670
MGMAT CAT 630
KAPLAN CAT 660

Manager
Joined: 10 May 2014
Posts: 142
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.
_________________

Consider giving me Kudos if I helped, but don´t take them away if I didn´t!

What would you do if you weren´t afraid?

Manager
Joined: 01 Jun 2013
Posts: 125
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
_________________

Please kindly click on "+1 Kudos", if you think my post is useful

Manager
Joined: 17 Mar 2014
Posts: 164
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."
_________________

KUDOS!!!, I need them too

Intern
Joined: 01 Aug 2015
Posts: 2
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.
Current Student
Joined: 20 Mar 2014
Posts: 2686
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
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 3939 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: 176
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
_________________

Regards,
Naveen
email: nkmungila@gmail.com
Please press kudos if you like this post

Senior Manager
Joined: 09 Mar 2016
Posts: 327
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;
Re: Among a group of 2,500 people, 35 percent invest in   [#permalink] 25 Feb 2018, 04:45
Display posts from previous: Sort by