GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 16 Jun 2019, 23:57

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

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

 
Senior Manager
Senior Manager
User avatar
Joined: 12 Aug 2015
Posts: 283
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, 03:54
11
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

78% (02:56) correct 22% (02:51) wrong based on 250 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%

_________________
KUDO me plenty
Retired Moderator
User avatar
D
Joined: 13 Apr 2015
Posts: 1681
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
GMAT ToolKit User
In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 02 Apr 2016, 04:16
2
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 2785 times ]

Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7743
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 02 Apr 2016, 05:16
1
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
_________________
Manager
Manager
avatar
G
Joined: 26 Dec 2015
Posts: 248
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, 17:19
Any addtl methods?

Not sure how to compute 10C1 and 250C1
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 55623
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 23 Jan 2017, 01:47
Manager
Manager
avatar
S
Joined: 04 Jun 2015
Posts: 79
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 27 Feb 2017, 02:00
1
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 2092 times ]


_________________
Sortem sternit fortem!
EMPOWERgmat Instructor
User avatar
V
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 14344
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 27 Feb 2017, 22:04
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:

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

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

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/
Manager
Manager
avatar
B
Joined: 31 Jan 2018
Posts: 69
GMAT 1: 700 Q46 V40
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 16 May 2018, 11:20
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%



Lets say there are 50 students in calculus, therefore number students in Trigonometry is 75(50% greater than number of students in calculus)

60 % of calculus students enrolled in beginner = 30 so there are 20 who were enrolled in advanced calculus

Total students = 50 + 75 = 125
Out of 125 total number of students enrolled in beginner class is 4/5 * 125 = 100

Out of 100, 30 enrolled for beginner calculus class and rest 70 enrolled for trigonometry beginner class, only 5 joined advanced trigonometry

so the probability that student selected is from advanced trigonometry is 5/125 * 100 = 4 %
GMATH Teacher
User avatar
P
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 936
In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 11 Oct 2018, 12:23
shasadou wrote:
In a certain math department, students are required to enroll in either Calculus or Trigonometry BUT NOT BOTH, 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%

\(? = \frac{{{\text{Trig}}\,\, \cap \,\,{\text{Adv}}}}{{{\text{Total}}}}\)

Good mix of the k technique with the grid (=double matrix, table, you-name-it)!

Image

\(?\,\,\, = \,\,\,\frac{k}{{25k}}\,\,\, = \,\,\,\frac{{1 \cdot \boxed4}}{{25 \cdot \boxed4}}\,\,\, = \,\,\,4\%\)

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 6521
Location: United States (CA)
Re: In a certain math department, students are required to enroll in eithe  [#permalink]

Show Tags

New post 18 Oct 2018, 18:22
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%



We can assume 60 students are enrolled in Trigonometry and thus 60/1.5 = 40 students are enrolled in Calculus. Furthermore, 0.6 x 40 = 24 students are enrolled in beginner Calculus and hence 16 students are enrolled in advanced Calculus.

Since there are a total of 60 + 40 = 100 students, 4/5 x 100 = 80 students are in the beginner courses. Since 24 students are enrolled in beginner Calculus, 80 - 24 = 56 students are enrolled in beginner Trigonometry. That means 60 - 56 = 4 students are enrolled in advanced Trigonometry. So the probability of selecting such a student at random is 4/100 = 4%.

Answer: A
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 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.

GMAT Club Bot
Re: In a certain math department, students are required to enroll in eithe   [#permalink] 18 Oct 2018, 18:22
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  


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