It is currently 19 Oct 2017, 15:45

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# A physics class has majors and non-majors in a ratio of 4 to

Author Message
TAGS:

### Hide Tags

Intern
Joined: 19 Jan 2010
Posts: 13

Kudos [?]: 24 [0], given: 16

A physics class has majors and non-majors in a ratio of 4 to [#permalink]

### Show Tags

02 Jun 2012, 18:01
3
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

86% (01:08) correct 14% (00:50) wrong based on 122 sessions

### HideShow timer Statistics

A physics class has majors and non-majors in a ratio of 4 to 10. If two more majors were to be added to the class, the ratio would then be 2 to 4. How many people are in the class?

A. 14
B. 28
C. 42
D. 56
E. 70
[Reveal] Spoiler: OA

Last edited by Bunuel on 22 Jul 2013, 04:53, edited 1 time in total.
Edited the OA.

Kudos [?]: 24 [0], given: 16

Math Expert
Joined: 02 Sep 2009
Posts: 41891

Kudos [?]: 128907 [1], given: 12183

Re: A physics class has majors and non-majors in a ratio of 4 to [#permalink]

### Show Tags

03 Jun 2012, 02:55
1
KUDOS
Expert's post
phoenix9801 wrote:

A physics class has majors and non-majors in a ratio of 4 to 10. If two more majors were to be added to the class, the ratio would then be 2 to 4. How many people are in the class?

A. 14
B. 28
C. 42
D. 56
E. 70

Given: $$\frac{majors}{non-majors}=\frac{4x}{10x}$$, for some positive multiple $$x$$.

Also: $$\frac{4x+2}{10x}=\frac{2}{4}$$ --> $$x=2$$ --> $$total=majors+non-majors=4x+10x=14x=28$$.

_________________

Kudos [?]: 128907 [1], given: 12183

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16652

Kudos [?]: 273 [0], given: 0

Re: A physics class has majors and non-majors in a ratio of 4 to [#permalink]

### Show Tags

04 Mar 2015, 10:55
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.
_________________

Kudos [?]: 273 [0], given: 0

EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9984

Kudos [?]: 3410 [0], given: 172

Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: A physics class has majors and non-majors in a ratio of 4 to [#permalink]

### Show Tags

04 Mar 2015, 18:09
Hi All,

While most Test Takers would approach this question with Algebra (which is fine), the numbers involved are relatively "easy", so you can get to the correct answer with a bit of Arithmetic and TESTing THE ANSWERS.

We're told that the starting ratio of majors:non-majors is 4:10, which means that the starting number of majors MUST be a multiple of 4, the starting number of non-majors MUST be a multiple of 10 and the total number of students MUST be a multiple of 14 (for every 14 total people, 4 are majors and 10 are non-majors).

We're told that by adding 2 more majors to the class, the ratio changes to 2:4. We're asked for the TOTAL number of students in the class.

14 total
4 majors
10 non-majors

4+2 = 6 majors
10 non-majors
majors:non-majors is 6:10 = 3:5, which is NOT what we're looking for.

Answer B: 28 total students....notice how this is EXACTLY DOUBLE the number in Answer A.....this should make some of the math go faster....
28 total
8 majors
20 non-majors

8+2 = 10 majors
20 non-majors
majors:non-majors = 10:20 = 2:4, which IS a match for what we were told.

[Reveal] Spoiler:
B

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!*********************** Kudos [?]: 3410 [0], given: 172 Veritas Prep GMAT Instructor Joined: 16 Oct 2010 Posts: 7674 Kudos [?]: 17361 [0], given: 232 Location: Pune, India Re: A physics class has majors and non-majors in a ratio of 4 to [#permalink] ### Show Tags 04 Mar 2015, 22:26 phoenix9801 wrote: A physics class has majors and non-majors in a ratio of 4 to 10. If two more majors were to be added to the class, the ratio would then be 2 to 4. How many people are in the class? A. 14 B. 28 C. 42 D. 56 E. 70 Another option is to simply use brute force with some logic: Say number of majors and non-majors are 4 and 10. If you add 2 more majors, you get 6 and 10. This ratio is higher than the required 1:2 so actual number of majors and non majors must be higher (so that the effect of 2 is slightly lower) Say, if number of majors and non majors are 4*2 and 10*2. If you add 2 more majors, you get 10 and 20. This is the required ratio. So total number = 8+20 = 28 Answer (B) _________________ Karishma Veritas Prep | GMAT Instructor My Blog Get started with Veritas Prep GMAT On Demand for$199

Veritas Prep Reviews

Kudos [?]: 17361 [0], given: 232

Re: A physics class has majors and non-majors in a ratio of 4 to   [#permalink] 04 Mar 2015, 22:26
Display posts from previous: Sort by