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

It is currently 19 Dec 2018, 08:25

TODAY:

MIT Sloan R1 Decisions - Join MIT Chat for Live Updates | Chat with UCLA Anderson Adcom @9am PT | Chat with Yale SOM R1 Admit 10am PT


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 in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Happy Christmas 20% Sale! Math Revolution All-In-One Products!

     December 20, 2018

     December 20, 2018

     10:00 PM PST

     11:00 PM PST

    This is the most inexpensive and attractive price in the market. Get the course now!
  • Key Strategies to Master GMAT SC

     December 22, 2018

     December 22, 2018

     07:00 AM PST

     09:00 AM PST

    Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

In a class of 120 students numbered 1 to 120, all even numbered studen

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51307
In a class of 120 students numbered 1 to 120, all even numbered studen  [#permalink]

Show Tags

New post 14 Mar 2016, 07:10
12
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

61% (02:54) correct 39% (02:50) wrong based on 141 sessions

HideShow timer Statistics

In a class of 120 students numbered 1 to 120, all even numbered students opt for Physics, those whose numbers are divisible by 5 opt for Chemistry and those whose numbers are divisible by 7 opt for Math. How many opt for none of the three subjects?

A. 19
B. 21
C. 26
D. 41
E. 57

_________________

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

SC Moderator
User avatar
D
Joined: 13 Apr 2015
Posts: 1688
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
GMAT ToolKit User Premium Member
Re: In a class of 120 students numbered 1 to 120, all even numbered studen  [#permalink]

Show Tags

New post 17 Mar 2016, 23:10
3
Total = 120

Total who study Physics = 120/2 = 60
Total who study Chemistry = 120/5 = 24
Total who study Math = 120/7 = 17

Students who study all 3 subjects = LCM (2, 5, 7) = 70x = 1
Students who study only Physics and Chemistry = LCM (2,5) = 10x = 12 - 1(students who study all 3) = 11
Students who study only Physics and Math = LCM(2, 7) = 14x = 8 - 1 = 7
Students who study only Chemistry and Math = LCM(5, 7) = 35x = 3 - 1 = 2

Students who study only Physics = 60 - 11 - 7 - 1 = 41
Students who study only Chemistry = 24 - 11 - 2 - 1 = 10
Students who study only Math = 17 - 7 - 2 - 1 = 7

Total who study atleast one subject = 1 + 11 + 7 + 2 + 41 + 10 + 7 = 79

None = Total - Total who study atleast one subject = 120 - 79 = 41

Answer: D
Manager
Manager
User avatar
S
Joined: 24 Jan 2017
Posts: 58
Re: In a class of 120 students numbered 1 to 120, all even numbered studen  [#permalink]

Show Tags

New post 16 Jul 2017, 21:37
1
Total number of students: 120
even: 60 -> Odd= 60
Divisible by 5: 120/5=24. Half of them are odd=12.
Divisible by 7: 120/7=17 ( we only care about the integer value). The number of odd numbers is either 8 or 9. To check, multiply 17*7. Since the product is odd, we know that the number of odd numbers is 9.
Divisible by both 7 and 5: 35,70,105. We only want the number of odd numbers=2.

Odd numbers=60
Odd numbers that are divisible by 5=12
Odd numbers that are divisible by 7=9
Odd numbers that are divisible by 7 and 5=2
Number of people who did not take any of the 3 classes=60-12-9+2=41
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: In a class of 120 students numbered 1 to 120, all even numbered studen  [#permalink]

Show Tags

New post 20 Jul 2017, 15:33
1
Bunuel wrote:
In a class of 120 students numbered 1 to 120, all even numbered students opt for Physics, those whose numbers are divisible by 5 opt for Chemistry and those whose numbers are divisible by 7 opt for Math. How many opt for none of the three subjects?

A. 19
B. 21
C. 26
D. 41
E. 57



Our goal is to find the number of students who do not opt for any of the three subjects. We first can find the number of students who do not opt for physics (i.e., eliminate the number of students who opt for it). Then, from those students, we eliminate those who opt for chemistry. Finally, from those who are left (after eliminating physics and chemistry), we eliminate those who opt for math. Thus, the students who are left are those who do not opt for any of the three subjects.

Since all even-numbered students (60 students) opt for physics, we know the odd-numbered students (the other 60 students) do not opt for physics. That is, the students numbered 1, 3, 5, …, 119 do not opt for physics. From these students, we see that the odd multiples of 5 (5, 15, 25, …, 115) opt for chemistry, and thus we have to eliminate them. The number of these students is:

(115 - 5)/10 + 1 = 12

Thus, we have 60 - 12 = 48 students left who do not opt for either physics or chemistry (or both). From these students, we need to eliminate those who are multiples of 7, since they opt for math. The numbers must be odd multiples of 7, namely, 7, 21, 35, 49, 63, 77, 91, 105, and 119. There are 9 such numbers. However, we see that we’ve already counted 35 and 105 since they are odd multiples of 5. Thus, there are 7 odd multiples of 7 that are not odd multiples of 5, and we have to exclude them. Thus, we have 48 - 7 = 41 students left and these students do not opt for any of the three subjects.

Answer: D
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 9207
Premium Member
Re: In a class of 120 students numbered 1 to 120, all even numbered studen  [#permalink]

Show Tags

New post 10 Aug 2018, 07:29
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

GMAT Club Bot
Re: In a class of 120 students numbered 1 to 120, all even numbered studen &nbs [#permalink] 10 Aug 2018, 07:29
Display posts from previous: Sort by

In a class of 120 students numbered 1 to 120, all even numbered studen

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.