Last visit was: 14 Dec 2024, 17:40 It is currently 14 Dec 2024, 17:40
Home
GMAT
Messages
Tests
Schools
Reviews
Social
Chat
My Profile
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,696
Own Kudos:
18,308
 []
Given Kudos: 165
Expert reply
Posts: 3,696
Kudos: 18,308
 []
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. Updated on: 30 Jan 2017, 00:26
Originally posted by EgmatQuantExpert on 30 Jan 2017, 00:17.
Last edited by EgmatQuantExpert on 30 Jan 2017, 00:26, edited 1 time in total.
1
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

88% (00:57) correct 12% (01:15) wrong based on 121 sessions

History

Date
Time
Result
Not Attempted Yet
A set X: {\(a_1, a_2, a_3, a_4, a_5\)} with non-zero elements have mean \(M\). What is the mean of the set Y: {\(a_1 - 1, a_2 - 2, a_3 - 3, a_4 + 5, a_5 + 1\)}?


    A. \(M - 3\)
    B. \(M - 2\)
    C. \(M - 1\)
    D. \(M\)
    E. \(M + 1\)

Thanks,
Saquib
Quant Expert
e-GMAT

Register for our Free Session on Number Properties (held every 3rd week) to solve exciting 700+ Level Questions in a classroom environment under the real-time guidance of our Experts :)

ShowHide Answer
Official Answer
D
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,696
Own Kudos:
18,308
Given Kudos: 165
Expert reply
Posts: 3,696
Kudos: 18,308
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. Updated on: 07 Feb 2017, 11:29
Originally posted by EgmatQuantExpert on 30 Jan 2017, 00:19.
Last edited by EgmatQuantExpert on 07 Feb 2017, 11:29, edited 1 time in total.
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The official solution has been posted. Looking forward to a healthy discussion..:)
User avatar
ankujgupta
User avatar
Joined: 21 Jan 2016
Last visit: 04 Aug 2018
Posts: 64
Own Kudos:
19
Given Kudos: 99
Location: India
GMAT 1: 670 Q50 V30
WE:Engineering (Computer Software)
GMAT 1: 670 Q50 V30
Posts: 64
Kudos: 19
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. 30 Jan 2017, 08:11
Kudos
Add Kudos
Bookmarks
Bookmark this Post
C. Sum of all the elements is same as original set. Hence mean is M
User avatar
ankujgupta
User avatar
Joined: 21 Jan 2016
Last visit: 04 Aug 2018
Posts: 64
Own Kudos:
19
Given Kudos: 99
Location: India
GMAT 1: 670 Q50 V30
WE:Engineering (Computer Software)
GMAT 1: 670 Q50 V30
Posts: 64
Kudos: 19
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. 30 Jan 2017, 11:03
Kudos
Add Kudos
Bookmarks
Bookmark this Post
ohmr
ankujgupta
C. Sum of all the elements is same as original set. Hence mean is M
I think you mean D
My bad. Yes it should be D .
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,696
Own Kudos:
18,308
Given Kudos: 165
Expert reply
Posts: 3,696
Kudos: 18,308
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. 07 Feb 2017, 11:28
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hey,

PFB the official solution. :)


To Find:

    • Mean of set Y

Working Out:

In Set X: {\(a_1, a_2, a_3, a_4, a_5\)}

    • Mean of Set X with 5 elements = \(M\)
    • Sum = Mean * Number of elements
    • \(a_1 + a_2 + a_3 + a_4 + a_5 = 5M\) (1)

In Set Y: {\(a_1 - 1, a_2 - 2, a_3 - 3, a_4 + 5, a_5 + 1\)}

    • Sum of elements \(= (a_1 – 1) + (a_2 – 2) + (a_3 – 3) + (a_4 + 5) + (a_5 + 1)\)
Rearranging, we get
    • Sum \(= a_1 + a_2 + a_3 + a_4 + a_5 + (-1 + -2 + -3 + 5 + 1)\)
    • Sum \(= a_1 + a_2 + a_3 + a_4 + a_5 + 0\)
    • Sum \(= 5M\) From(1)
    • Mean\(= \frac{(Sum)}{(Number of elements)}\)
    • Mean \(= \frac{5M}{5}\)
    • Mean \(= M\)

Correct Answer: Option D


Thanks,
Saquib
Quant Expert
e-GMAT

Register for our Free Session on Number Properties (held every 3rd week) to solve exciting 700+ Level Questions in a classroom environment under the real-time guidance of our Experts :)

User avatar
nks2611
User avatar
Joined: 24 Oct 2016
Last visit: 06 Apr 2020
Posts: 194
Own Kudos:
67
Given Kudos: 89
Location: India
Concentration: Finance, International Business
Schools: IIMB
GMAT 1: 550 Q42 V28
GPA: 3.96
WE:Human Resources (Retail Banking)
Schools: IIMB
GMAT 1: 550 Q42 V28
Posts: 194
Kudos: 67
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. 02 Mar 2017, 05:05
Kudos
Add Kudos
Bookmarks
Bookmark this Post
choose simple no such as 1,2,3,4,5 so average will be 3 now follow the process you will get 0+0+0+9+6=15/5=3 so answer would be D
avatar
Shiv2016
avatar
Joined: 02 Sep 2016
Last visit: 14 Aug 2024
Posts: 522
Own Kudos:
202
Given Kudos: 277
Posts: 522
Kudos: 202
A set X: {a1, a2, a3, a4, a5} with non-zero elements have mean M. 03 Apr 2017, 05:14
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Set X:
Mean=M= (a1+a2+a3+a4+a5)/5
Sum of these values= 5M

Set Y:
We see similar elements a1, a2, ...........
Combine them together and we know that their sum is equal to 5M.

Therefore
5M-1-2-3+5+1
=5M+0
=5M

The mean of set Y= 5M/5=M

Mean of set X=Mean of set Y
Moderator:
Bunuel
Math Expert
97877 posts