It is currently 20 Feb 2018, 11:46

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

In a certain math department, students are required to enroll in eithe

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Current Student
User avatar
Joined: 12 Aug 2015
Posts: 297
Concentration: General Management, Operations
GMAT 1: 640 Q40 V37
GMAT 2: 650 Q43 V36
GMAT 3: 600 Q47 V27
GPA: 3.3
WE: Management Consulting (Consulting)
In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 02 Apr 2016, 02:54
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

63% (02:03) correct 37% (02:28) wrong based on 124 sessions

HideShow timer Statistics

In a certain math department, students are required to enroll in either Calculus or Trigonometry, each of which is offered in beginner and advanced courses. The number of students enrolled in Trigonometry is 50% greater than the number of students enrolled in Calculus, and 60% of Calculus students are enrolled in the beginner course. If 4/5 of students are in the beginner courses, and one student is selected at random, what is the probability that an advanced Trigonometry student is selected?

A. 4%
B. 16%
C. 20%
D. 24%
E. 40%
[Reveal] Spoiler: OA

_________________

KUDO me plenty

1 KUDOS received
SC Moderator
User avatar
P
Joined: 13 Apr 2015
Posts: 1580
Location: India
Concentration: Strategy, General Management
WE: Analyst (Retail)
GMAT ToolKit User Premium Member CAT Tests
In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 02 Apr 2016, 03:16
1
This post received
KUDOS
Let number of students enrolled in calculus = x
Number of students enrolled in Trigonometry = 1.5x
Total number of students = x + 1.5x = 2.5x


Number of students enrolled in beginner calculus course = 0.6x
4/5 of Total are in beginner courses --> Number of students in beginner courses = (4/5)*2.5x = 2x
Number of students enrolled in beginner trigonometry courses = 2x - 0.6x = 1.4x

Number of students in advanced calculus courses = x - 0.6x = 0.4x
Number of students in advanced trigonometry courses = 1.5x - 1.4x = 0.1x

Probability that an advanced Trigonometry student is selected = (Number of ways of selecting one student from advanced trigonometry course)/(Number of ways of selecting one student from total)

Assume x = 100

Probability = 10C1/250C1 = 10/250 = 1/25 = 4%

Answer: A
Attachments

IMG_20160402_163946.jpg
IMG_20160402_163946.jpg [ 1.6 MiB | Viewed 1472 times ]

Expert Post
1 KUDOS received
Math Expert
User avatar
D
Joined: 02 Aug 2009
Posts: 5658
Re: In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 02 Apr 2016, 04:16
1
This post received
KUDOS
Expert's post
shasadou wrote:
In a certain math department, students are required to enroll in either Calculus or Trigonometry, each of which is offered in beginner and advanced courses. The number of students enrolled in Trigonometry is 50% greater than the number of students enrolled in Calculus, and 60% of Calculus students are enrolled in the beginner course. If 4/5 of students are in the beginner courses, and one student is selected at random, what is the probability that an advanced Trigonometry student is selected?

A. 4%
B. 16%
C. 20%
D. 24%
E. 40%


Hi,
Vyshak has told you the exact method ..

However if you get this in exam and are unable to move ahead, you can make intelligent guess..
since ONLY 1/5 of students are in ADVANCED course, picking a advanced course student itself is 1/2 or 20%..
so our answer has to be less than 20%...
so A and B are left...
This was easy to get probability up from 1/5 to 1/2 of getting the answer correct

The second step requires a bit of visualization
Now calculus : trig = 2:3..
so 40 % of C added with 16% of T should give a value > 20%, when their ratios are 2:3
SO ans 4%
A
A
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html


BANGALORE/-

Senior Manager
Senior Manager
avatar
G
Joined: 26 Dec 2015
Posts: 285
Location: United States (CA)
Concentration: Finance, Strategy
WE: Investment Banking (Venture Capital)
Re: In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 22 Jan 2017, 16:19
Any addtl methods?

Not sure how to compute 10C1 and 250C1
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 43831
Re: In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 23 Jan 2017, 00:47
LakerFan24 wrote:
Any addtl methods?

Not sure how to compute 10C1 and 250C1


C stands for combinations. 10C1 = 10!/(1!*(10-1)!) = 10 and 250C1 = 250!/(1!*(250-1)!) = 250.

Combinatorics Made Easy!

Theory on Combinations

DS questions on Combinations
PS questions on Combinations

Hope it helps.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Manager
Manager
avatar
S
Joined: 03 Jun 2015
Posts: 86
Re: In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 27 Feb 2017, 01:00
shasadou wrote:
In a certain math department, students are required to enroll in either Calculus or Trigonometry, each of which is offered in beginner and advanced courses. The number of students enrolled in Trigonometry is 50% greater than the number of students enrolled in Calculus, and 60% of Calculus students are enrolled in the beginner course. If 4/5 of students are in the beginner courses, and one student is selected at random, what is the probability that an advanced Trigonometry student is selected?

A. 4%
B. 16%
C. 20%
D. 24%
E. 40%



Solve for C. Please see the attachment.

C+1.5C = 100
C = 40.

Substitute C = 40 wherever indicated. In the "advanced" box you'll get 16 + 4 = 20.
Probability will be 4/100 or 4%.
Attachments

Cal&Tri.png
Cal&Tri.png [ 13.77 KiB | Viewed 794 times ]


_________________

Sortem sternit fortem!

Expert Post
EMPOWERgmat Instructor
User avatar
D
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11036
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: In a certain math department, students are required to enroll in eithe [#permalink]

Show Tags

New post 27 Feb 2017, 21:04
Hi All,

This question can be solved by TESTing VALUES and taking the proper notes.

We're told that there are two classes (Calculus and Trigonometry) and each is offered in beginner and advanced courses - and that each student is enrolled in just one course.

The number of students enrolled in Trigonometry is 50% greater than the number of students enrolled in Calculus....

IF.... there are 100 total students
Trigonometry = 60 students
Calculus = 40 students

....and 60% of Calculus students are enrolled in the beginner course....

Calculus = 40 total students
-Beginner = 60% of 40 = 24 students
-Advanced = 40 - 24 = 16 students

... and 4/5 of students are in the beginner courses....

4/5 of 100 = 80 students in beginner courses
-Beginning Calculus = 24 students
-Beginning Trigonometry = 80 - 24 = 56 students

Since there are 60 total Trigonometry students, and 56 of them are in the beginner course, 60 - 56 = 4 students in the advanced Trigonometry course

We're asked for the probability that an advanced Trigonometry student is selected? That would be 4/100 = 4%

Final Answer:
[Reveal] Spoiler:
A


GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Re: In a certain math department, students are required to enroll in eithe   [#permalink] 27 Feb 2017, 21:04
Display posts from previous: Sort by

In a certain math department, students are required to enroll in eithe

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

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

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®.