GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video
close
It is currently 11 May 2021, 20:42
Register
GMAT Club Tests
Decision Tracker
My Rewards
New posts
New comers' posts

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.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
Of the N students in a certain class, X took a course in biology and Y
6 posts Go to First Unread Post
Print view
NEW TOPIC
POST REPLY
Downloads
My Bookmarks
Reviews
SORT BY:
Date
Kudos
Tags:
Find Similar Topics 

Show Tags
Hide Tags

User avatar
V
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 74751
CAT Tests Top Member of the Month
Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  06 Dec 2019, 04:08
1
Kudos
4
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

45% (medium)

Question Stats:

66% (02:13) correct 34% (02:27) wrong based on 100 sessions

Hide Show timer Statistics

Of the N students in a certain class, X took a course in biology and Y took a course in history, and Z took neither of the courses. If there were students who took both two courses, in terms of N, X, Y and Z, what fraction of the students took both two courses?


(A) \(1 - \frac{X+Y+Z}{N}\)

(B) \(\frac{X+Y+Z}{N} - 1\)

(C) \(\frac{X+Y-Z-N}{N}\)

(D) \(\frac{N+X+Y-Z}{N}\)

(E) \(\frac{N-X-Y+Z}{N}\)


Are You Up For the Challenge: 700 Level Questions
ShowHide Answer
Official Answer
Official Answer and Stats are available only to registered users. Register/Login.

_________________
New to the GMAT CLUB Forum?
Posting Rules: QUANTITATIVE | VERBAL. Guides and Resources: QUANTITATIVE | VERBAL | Ultimate GMAT Quantitative Megathread | All You Need for Quant

Questions' Banks and Collection:
PS: Standard deviation | Tough Problem Solving Questions With Solutions | Probability and Combinations Questions With Solutions | Tough and tricky exponents and roots questions | 12 Easy Pieces (or not?) | Bakers' Dozen | Algebra set | Mixed Questions | Fresh Meat
DS: DS Standard deviation | Inequalities | 700+ GMAT Data Sufficiency Questions With Explanations | Tough and tricky exponents and roots questions | The Discreet Charm of the DS | Devil's Dozen!!! | Number Properties set | New DS set
MIXED: GMAT Club's Complete Questions' Bank | SEVEN SAMURAI OF 2012 | Tricky questions from previous years. | Special Questions' Directory | Best Of The Best Of 2017 | The Best Of Quant of 2016 | 20 hardest and 20 best questions of 2015 | 15 best topics of 2015 | Seven Samurai of 2012 | GMAT Probability Questions

What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
User avatar
G
Ansh777
Manager
Manager
Joined: 03 Nov 2019
Posts: 71
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  06 Dec 2019, 04:25
1
Kudos
N-Z=X+Y-Both
Both= X+Y-N+Z

Both/N= (X+Y-N+Z)/N

Answer: B

Posted from my mobile device
User avatar
V
Archit3110
GMAT Club Legend
GMAT Club Legend
Joined: 18 Aug 2017
Status:You learn more from failure than from success.
Posts: 6979
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE:Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member Reviews Badge
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  07 Dec 2019, 01:59
make 2x2 matrix

---B-----NB---total
H--(y-(n-x)-z)---(n-x)-z---y
NH--(n-y)-z---z----n-y
total--x----n-x---n
fraction
(y-(n-x)-z)/n
or say
x+y+z-n/n ;
\(\frac{X+Y+Z}{N} - 1\)
IMO B


Bunuel wrote:
Of the N students in a certain class, X took a course in biology and Y took a course in history, and Z took neither of the courses. If there were students who took both two courses, in terms of N, X, Y and Z, what fraction of the students took both two courses?


(A) \(1 - \frac{X+Y+Z}{N}\)

(B) \(\frac{X+Y+Z}{N} - 1\)

(C) \(\frac{X+Y-Z-N}{N}\)

(D) \(\frac{N+X+Y-Z}{N}\)

(E) \(\frac{N-X-Y+Z}{N}\)


Are You Up For the Challenge: 700 Level Questions
User avatar
G
TestPrepUnlimited
GMAT Tutor
Joined: 16 Sep 2014
Posts: 1052
Location: United States
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  07 Dec 2019, 09:24
Expert Reply
Bunuel wrote:
Of the N students in a certain class, X took a course in biology and Y took a course in history, and Z took neither of the courses. If there were students who took both two courses, in terms of N, X, Y and Z, what fraction of the students took both two courses?


(A) \(1 - \frac{X+Y+Z}{N}\)

(B) \(\frac{X+Y+Z}{N} - 1\)

(C) \(\frac{X+Y-Z-N}{N}\)

(D) \(\frac{N+X+Y-Z}{N}\)

(E) \(\frac{N-X-Y+Z}{N}\)

Are You Up For the Challenge: 700 Level Questions


If there are two categories A and B, we have the formula Total = A + B - Both + Neither. To go into detail, the A category includes "A only" and "Both A and B". The B category includes "B only" and "Both A and B". So we double-counted "Both" if we just add everything up, hence we take it away once from the total. Here we want to find both,

Both = A + B + Neither - Total = X + Y + Z - N.
Finally, the fraction out of the total of N would be \(\frac{{X + Y + Z - N} }{ N} = \frac{{X + Y + Z} }{ N} - 1\). The answer would be B.
_________________
Source: We are an NYC based, in-person and online GMAT tutoring and prep company. We are the only GMAT provider in the world to guarantee specific GMAT scores with our flat-fee tutoring packages, or to publish student score increase rates. Our typical new-to-GMAT student score increase rate is 3-9 points per tutoring hour, the fastest in the world. Feel free to reach out!
Signature Read More
User avatar
V
Kinshook
GMAT Club Legend
GMAT Club Legend
Joined: 03 Jun 2019
Posts: 4330
Location: India
Schools: HBS '22, CBS '22, Wharton '22
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Reviews Badge
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  07 Dec 2019, 09:45
1
Kudos
1
Bookmarks
Bunuel wrote:
Of the N students in a certain class, X took a course in biology and Y took a course in history, and Z took neither of the courses. If there were students who took both two courses, in terms of N, X, Y and Z, what fraction of the students took both two courses?


(A) \(1 - \frac{X+Y+Z}{N}\)

(B) \(\frac{X+Y+Z}{N} - 1\)

(C) \(\frac{X+Y-Z-N}{N}\)

(D) \(\frac{N+X+Y-Z}{N}\)

(E) \(\frac{N-X-Y+Z}{N}\)


Are You Up For the Challenge: 700 Level Questions


N = X + Y - Both +Z
Both = X + Y + Z - N

Fraction of students who took both the courses = (X + Y + Z - N)/N = (X+Y+Z)/N - 1

IMO B
_________________
Kinshook Chaturvedi
Email: kinshook.chaturvedi@gmail.com
Signature Read More
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 18999
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink] New post  10 Dec 2020, 03:47
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources
Signature Read More
GMAT Club Bot
gmatclubot
Re: Of the N students in a certain class, X took a course in biology and Y [#permalink]
10 Dec 2020, 03:47
NEW TOPIC
POST REPLY
Downloads
My Bookmarks
Reviews
Moderators:
chetan2u
Math Expert
9821 posts
Bunuel
Math Expert
74751 posts
yashikaaggarwal
Senior Moderator - Masters Forum
2463 posts
generis
Senior SC Moderator
4729 posts

cron

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions