Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 26 May 2017, 11:58

### 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

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

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 07 Nov 2009
Posts: 306
Followers: 9

Kudos [?]: 592 [1] , given: 20

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

### Show Tags

26 Jan 2012, 12:32
1
KUDOS
1
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

74% (01:45) correct 26% (01:05) wrong based on 227 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%
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Sep 2009
Posts: 38908
Followers: 7739

Kudos [?]: 106225 [1] , given: 11618

### Show Tags

26 Jan 2012, 12:39
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
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: 17
Followers: 0

Kudos [?]: 0 [0], given: 11

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?
_________________

regards
eshwar

Math Expert
Joined: 02 Sep 2009
Posts: 38908
Followers: 7739

Kudos [?]: 106225 [1] , given: 11618

Re: What is the minimum percentage increase in the mean of set X [#permalink]

### Show Tags

26 Mar 2012, 09:18
1
KUDOS
Expert's post
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: 1857
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Followers: 51

Kudos [?]: 2172 [0], given: 193

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
_________________

Kindly press "+1 Kudos" to appreciate

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15465
Followers: 649

Kudos [?]: 209 [0], given: 0

Re: What is the minimum percentage increase in the mean of set X [#permalink]

### Show Tags

08 Jul 2016, 06:12
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.
_________________
Director
Joined: 04 Jun 2016
Posts: 654
GMAT 1: 750 Q49 V43
Followers: 63

Kudos [?]: 277 [0], given: 36

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.

VP
Joined: 12 Sep 2015
Posts: 1433
Followers: 138

Kudos [?]: 1626 [1] , given: 328

Re: What is the minimum percentage increase in the mean of set X [#permalink]

### Show Tags

17 Sep 2016, 04:45
1
KUDOS
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

_________________

Brent Hanneson – Founder of gmatprepnow.com

Senior Manager
Joined: 11 Nov 2014
Posts: 370
Location: India
WE: Project Management (Telecommunications)
Followers: 2

Kudos [?]: 30 [0], given: 17

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...
BSchool Forum Moderator
Status: Aiming 800 Q51 V51
Joined: 18 Jul 2015
Posts: 1680
Location: India
GMAT 1: 670 Q50 V32
GMAT 2: 700 Q50 V34
GPA: 3.65
WE: Brand Management (Health Care)
Followers: 39

Kudos [?]: 400 [0], given: 51

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.
_________________

Good Luck

Senior Manager
Joined: 26 Oct 2016
Posts: 460
Location: United States
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
Followers: 25

Kudos [?]: 63 [0], given: 823

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
Followers: 0

Kudos [?]: 1 [1] , given: 0

Re: What is the minimum percentage increase in the mean of set X {-4, -1, [#permalink]

### Show Tags

08 Dec 2016, 20:43
1
KUDOS
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: 38908
Followers: 7739

Kudos [?]: 106225 [0], given: 11618

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.
_________________
Re: What is the minimum percentage increase in the mean of set X   [#permalink] 09 Dec 2016, 02:09
Similar topics Replies Last post
Similar
Topics:
16 What is the minimum value of |x-4| + |x+3| + |x-5| ? 8 24 May 2017, 14:30
10 Randy is going to flip a coin x times. What is the minimum value of x 8 04 Nov 2016, 08:23
6 What will be the percentage increase in the area of the cube 7 11 Jan 2016, 09:11
8 What is the minimum value of the function y=x^2-4x-5 8 20 Nov 2015, 06:55
2 A set has maximum number 4d above the mean and a minimum 3 22 Jan 2011, 11:26
Display posts from previous: Sort by