It is currently 03 Jul 2020, 14:32
My Tests

The 4th of July -

The Independence Day FULL Access to the Tests !!


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.

QOTD # 11 Of the students in a school, 20 percent are in the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Founder
Founder
User avatar
Joined: 18 Apr 2015
Posts: 11932
Followers: 250

Kudos [?]: 2967 [0], given: 11171

QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 13 Sep 2016, 06:11
Expert's post
00:00

Question Stats:

58% (01:43) correct 41% (02:03) wrong based on 70 sessions
Of the students in a school, 20 percent are in the science club and 30 percent are in the band. If 25 percent of the students in the school are in the band but are not in the science club, what percent of the students who are in the science club are not in the band?


A) 5%
B) 20%
C) 25%
D) 60%
E) 75%

Practice Questions
Question: 11
Page: 204
[Reveal] Spoiler: OA

_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

2 KUDOS received
GRE Instructor
User avatar
Joined: 10 Apr 2015
Posts: 3515
Followers: 133

Kudos [?]: 3947 [2] , given: 65

CAT Tests
Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 20 Sep 2016, 12:13
2
This post received
KUDOS
Expert's post
Explanation


Use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions).
Here, we have a population of students, and the two characteristics are:
- in the science club or not in the science club
- in the band or not in the band

So, we can set up our matrix as follows:
Image

Since we aren't told the total population AND we're asked to find a percentage, let's say that the TOTAL population is 100 (an easy number to work with)
Image

20 percent of the students are in the science club, and 30 percent of the students are in the band
Since the total population is 100, this means that there are 20 students in the science club. Also, since there are 100 students, we can conclude that 80 students are NOT in teh science club.
Likewise, if 30 students are in the band, then 70 students are NOT in the band.
So, let's add all of this to the diagram:
Image

25 percent of the students in the school are in the band but are not in the science club
Great. We'll add this to our diagram:
Image

Since the two boxes in the left-hand column must add to 30, we can see that the top box must hold 5 students
Image

Since the two boxes in the top row must add to 20, we can see that the top right box must hold 15 students
Image

Using similar logic, we can see that the last box holds 55 students
Image

What percent of the students who are in the science club are not in the band?
Our diagram tells us that there are 20 students in the science club.
Of those 20 students, 15 are NOT in the band.
15/20 = 75%

Answer: E

RELATED VIDEO

_________________

Brent Hanneson – Creator of greenlighttestprep.com
Sign up for my free GRE Question of the Day emails
Image

1 KUDOS received
Founder
Founder
User avatar
Joined: 18 Apr 2015
Posts: 11932
Followers: 250

Kudos [?]: 2967 [1] , given: 11171

Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 30 Dec 2019, 12:34
1
This post received
KUDOS
Expert's post
Let there be 100 students in the school.

Number of Students in Science Club= 20.
Number of students in Band = 30.
Number of students in a band but not science club= 25.

Number of students in a band and science club= 5.

No of students that are in science club but not in a band= 20 -5 =15.

% of students that are in science club but not in a band = \(\frac{15}{20}*100\) =75
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos
GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests.

Intern
Intern
Joined: 01 Mar 2020
Posts: 6
Followers: 0

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

Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 09 May 2020, 11:24
Hi Brent,

Would the answer have been 15% if the question asked "what percent of students are in the science club but are not in the band?" So in this case it would be students who are in science but not in band over the total number of students. I think the reason I got confused with the original question was because I was finding the percentage of students who were in science and not in band from the overall total number of students instead of calculating the percent as a total of students who took Science.


[quote="GreenlightTestPrep"]Explanation
1 KUDOS received
GRE Instructor
User avatar
Joined: 10 Apr 2015
Posts: 3515
Followers: 133

Kudos [?]: 3947 [1] , given: 65

CAT Tests
Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 09 May 2020, 13:20
1
This post received
KUDOS
Expert's post
GREStudent2020 wrote:
Hi Brent,

Would the answer have been 15% if the question asked "what percent of students are in the science club but are not in the band?" So in this case it would be students who are in science but not in band over the total number of students. I think the reason I got confused with the original question was because I was finding the percentage of students who were in science and not in band from the overall total number of students instead of calculating the percent as a total of students who took Science.



That's correct.
15 percent of all students are in the science club but not in the band.

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com
Sign up for my free GRE Question of the Day emails
Image

Intern
Intern
Joined: 15 Mar 2019
Posts: 5
Followers: 0

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

Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 29 Jun 2020, 04:58
15%
Intern
Intern
Joined: 15 Mar 2019
Posts: 5
Followers: 0

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

Re: QOTD # 11 Of the students in a school, 20 percent are in the [#permalink] New post 29 Jun 2020, 04:59
But I could be wrong
Re: QOTD # 11 Of the students in a school, 20 percent are in the   [#permalink] 29 Jun 2020, 04:59
Display posts from previous: Sort by

QOTD # 11 Of the students in a school, 20 percent are in the

  Question banks Downloads My Bookmarks Reviews Important topics  


GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.