GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 26 Jan 2020, 01:29

### 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

# What is the minimum percentage increase in the mean of set X

Author Message
TAGS:

### Hide Tags

Manager
Joined: 07 Nov 2009
Posts: 213
What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

26 Jan 2012, 12:32
1
4
00:00

Difficulty:

25% (medium)

Question Stats:

72% (01:21) correct 28% (01:48) wrong based on 231 sessions

### HideShow timer Statistics

What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 200%
Math Expert
Joined: 02 Sep 2009
Posts: 60647

### Show Tags

26 Jan 2012, 12:39
2
rohitgoel15 wrote:
What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 200%

Mean of X is (-4-1+0+6+9)/5=2;

In order the increase to be minimal we should replace two smallest elements of X, which are -4 and -1, with two smallest primes, which are 2 and 3. Hence our new set will be {2, 3, 0, 6, 9} --> new mean is (2+3+0+6+9)/5=4.

Percent increase=(4-2)/2*100=100%.

_________________
Intern
Joined: 25 Aug 2010
Posts: 16
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

26 Mar 2012, 09:10
hi Bunuel,

request to let me if two smallest primes numbers can be negative?
Math Expert
Joined: 02 Sep 2009
Posts: 60647
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

26 Mar 2012, 09:18
1
pappueshwar wrote:
hi Bunuel,

request to let me if two smallest primes numbers can be negative?

Only positive numbers can be primes, so the smallest prime is 2.

Hope it helps.
_________________
SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1723
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

01 Mar 2013, 03:09
1 is not a prime number, got to know it now..... was considering it & made the answer wrong
Director
Joined: 04 Jun 2016
Posts: 540
GMAT 1: 750 Q49 V43
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

23 Jul 2016, 01:08
rohitgoel15 wrote:
What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 200%

Current mean is =$$\frac{(-4)+(-1)+(0)+(6)+(9)}{5} = \frac{(-5+15)}{5} = \frac{10}{5} = 2$$

Since we have to find the minimum increase , we should add the smallest distinct prime 2,3
New mean is =$$\frac{(0)+(2)+(3)+(6)+(9)}{5} = \frac{20}{5} = 4$$

Percent change = $$\frac{(New -Old}{Old})* 100 = \frac{4-2}{2}*100$$

Percent change = $$\frac{2}{2}* 100 = 100$$ %

_________________
Posting an answer without an explanation is "GOD COMPLEX". The world doesn't need any more gods. Please explain you answers properly.
FINAL GOODBYE :- 17th SEPTEMBER 2016. .. 16 March 2017 - I am back but for all purposes please consider me semi-retired.
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 4226
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

17 Sep 2016, 04:45
1
Top Contributor
As others have demonstrated, the average of set X increases from 2 to 4
Many students will incorrectly conclude that we have a 200% increase, since 4 is equal to 2 times 2.
This is not the case.
Percent increase = 100(new - old)/old
So, in this case, percent increase = 100(4 - 2)/2
= 200/2
= 100

RELATED VIDEO

_________________
Test confidently with gmatprepnow.com
Senior Manager
Joined: 11 Nov 2014
Posts: 305
Location: India
WE: Project Management (Telecommunications)
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

17 Sep 2016, 07:48
Bunuel
answer will change if I have 5 & 2 or say 2 & 11, isn't it?
just curious...
Board of Directors
Status: Stepping into my 10 years long dream
Joined: 18 Jul 2015
Posts: 3554
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

17 Sep 2016, 07:51
paidlukkha wrote:
Bunuel
answer will change if I have 5 & 2 or say 2 & 11, isn't it?
just curious...

Yes, it will change but notice that we have to determine the minimum change and for that we are taking the lowest possible values as 2 and 3.
_________________
My GMAT Story: From V21 to V40
My MBA Journey: My 10 years long MBA Dream
My Secret Hacks: Best way to use GMATClub | Importance of an Error Log!
Verbal Resources: All SC Resources at one place | All CR Resources at one place

GMAT Club Inbuilt Error Log Functionality - View More.
New Visa Forum - Ask all your Visa Related Questions - here.
New! Best Reply Functionality on GMAT Club!
Find a bug in the new email templates and get rewarded with 2 weeks of GMATClub Tests for free
Check our new About Us Page here.
Director
Joined: 26 Oct 2016
Posts: 599
Location: United States
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
What is the minimum percentage increase in the mean of set X {-4, -1,  [#permalink]

### Show Tags

08 Dec 2016, 19:58
What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25% (B) 50% (C) 75% (D) 100% (E) 200%

Stuck with above problem looking for some guidance and assistance.
_________________
Thanks & Regards,
Anaira Mitch
Intern
Joined: 21 Jul 2016
Posts: 1
Re: What is the minimum percentage increase in the mean of set X {-4, -1,  [#permalink]

### Show Tags

08 Dec 2016, 20:43
1
I think D.
Mean in the initial set is 2 (-4-2+0+6+9)/5. We should replace the smallest elements -4 and -1 with prime numbers also the smallest in order to have minimum percentage increase. So we get new set (2,3,0,6,9) with mean 4. So the minimum % increase is 100%

Sent from my SM-A310F using GMAT Club Forum mobile app
Math Expert
Joined: 02 Sep 2009
Posts: 60647
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

09 Dec 2016, 02:09
anairamitch1804 wrote:
What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25% (B) 50% (C) 75% (D) 100% (E) 200%

Stuck with above problem looking for some guidance and assistance.

Merging topics. Please refer to the discussion above.
_________________
Director
Joined: 12 Nov 2016
Posts: 691
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

13 Jul 2017, 15:34
rohitgoel15 wrote:
What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 200%

minimize set [2, 3, 0 ,6, 9] = 20/5= 4

old set [-4,-1,0,6,9] = 10/5 =2

4-2/2 = 1

D
Non-Human User
Joined: 09 Sep 2013
Posts: 14013
Re: What is the minimum percentage increase in the mean of set X  [#permalink]

### Show Tags

08 Dec 2019, 03:02
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.
_________________
Re: What is the minimum percentage increase in the mean of set X   [#permalink] 08 Dec 2019, 03:02
Display posts from previous: Sort by