Last visit was: 08 Jul 2025, 19:55 It is currently 08 Jul 2025, 19:55
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
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 08 Jul 2025
Posts: 102,594
Own Kudos:
Given Kudos: 97,452
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,594
Kudos: 739,580
 [44]
1
Kudos
Add Kudos
43
Bookmarks
Bookmark this Post
User avatar
FieryLeo
Joined: 28 Jul 2011
Last visit: 02 Apr 2025
Posts: 22
Own Kudos:
Given Kudos: 5
Location: United Kingdom
WE:Corporate Finance (Energy)
Posts: 22
Kudos: 52
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
LeonidK
Joined: 28 Jul 2016
Last visit: 29 Nov 2018
Posts: 122
Own Kudos:
Given Kudos: 42
Posts: 122
Kudos: 40
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
jfranciscocuencag
Joined: 12 Sep 2017
Last visit: 17 Aug 2024
Posts: 230
Own Kudos:
Given Kudos: 132
Posts: 230
Kudos: 136
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Set A consists of the the first 10 terms of a sequence. For which sequence, in which \(a_n=x\) defines how the nth term is calculated, will set A have the greatest standard deviation?

A. \(a_n=n^2\)

B. \(a_n=2n+50\)

C. \(a_n=\frac{n}{3}\)

D. \(a_n=n^3−60\)

E. \(a_n=2n+100\)

Hello Bunuel !

Just one question, do the numbers that are being added/subtracted have a specific meaning?

A. \(a_n=n^2\)

B. \(a_n=2n+50\)

C. \(a_n=\frac{n}{3}\)

D. \(a_n=n^3−60\)

E. \(a_n=2n+100\)[/quote]


Kind regards!
User avatar
energetics
Joined: 05 Feb 2018
Last visit: 09 Oct 2020
Posts: 298
Own Kudos:
904
 [3]
Given Kudos: 325
Posts: 298
Kudos: 904
 [3]
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I think the numbers are arbitrary, we're not given the actual sequence so we can make up our own, like {1,2,3,5,6,7,8,9,10}.
Then plug in n=1 for first and n=10 for last term:
A) 1 to 100
B) 52 to 70
C) 1/3 to 10/3
D) -59 to 940
E) 102 to 300

We can see that D) has the largest range, and in our evenly spaced set the distance between each part of the set (the standard deviation) will be largest in D): 999/10 = 99.9 between each point.
avatar
brianmontanaweb
Joined: 06 Apr 2022
Last visit: 03 Sep 2022
Posts: 116
Own Kudos:
Given Kudos: 22
Posts: 116
Kudos: 15
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Set A consists of the the first 10 terms of a sequence. For which sequence, in which \(a_n=x\) defines how the nth term is calculated, will set A have the greatest standard deviation?

A. \(a_n=n^2\)

B. \(a_n=2n+50\)

C. \(a_n=\frac{n}{3}\)

D. \(a_n=n^3−60\)

E. \(a_n=2n+100\)

Taking only the first and last value in the set, 1 and 100, to determine the standard deviation in the set.

A and D both look the most promising for variation, so focusing on those. Eliminating B, C, and E through quick mental math.

\(a_1=1^2\) = 1
\(a_10=10^2\) = 100

A can move from 1 to 100.

\(a_1=1^3−60\) = -59
\(a_10=10^3−60\) = 940

D has the largest standard deviation between the two. D wins!
User avatar
Nefertiti9
Joined: 27 Oct 2021
Last visit: 18 Aug 2022
Posts: 110
Own Kudos:
Given Kudos: 130
Location: India
Posts: 110
Kudos: 58
Kudos
Add Kudos
Bookmarks
Bookmark this Post
IMO D,
I did not use notebook for this one , not sure if my method was correct.
I ignored whatever was +100 or -50 in options as that is going to be same in all terms.
Also if all terms are multiplied by something S.D. is also multiplied by it and here \(n3\) is the biggest multiplication happening .
User avatar
NirupaD
Joined: 15 Oct 2019
Last visit: 11 Jul 2024
Posts: 69
Own Kudos:
Given Kudos: 81
Products:
Posts: 69
Kudos: 45
Kudos
Add Kudos
Bookmarks
Bookmark this Post
jfranciscocuencag
Bunuel
Set A consists of the the first 10 terms of a sequence. For which sequence, in which \(a_n=x\) defines how the nth term is calculated, will set A have the greatest standard deviation?

A. \(a_n=n^2\)

B. \(a_n=2n+50\)

C. \(a_n=\frac{n}{3}\)

D. \(a_n=n^3−60\)

E. \(a_n=2n+100\)

Hello Bunuel !

Just one question, do the numbers that are being added/subtracted have a specific meaning?

A. \(a_n=n^2\)

B. \(a_n=2n+50\)

C. \(a_n=\frac{n}{3}\)

D. \(a_n=n^3−60\)

E. \(a_n=2n+100\)


Kind regards![/quote]



When finding standard daviation, addition or subtraction of same number in entire set will not influence SD. However if you multiply or divide, SD will multiply and divide in same manner.

In this case addition or subtraction of 50, 60 and 100 in elements will not change SD. so ignore such part. I hope that answers your question.

exa set1 {1,2,3} have same SD as set2 {50,51,52}(added 50 in set1)
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,358
Own Kudos:
Posts: 37,358
Kudos: 1,010
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderators:
Math Expert
102594 posts
PS Forum Moderator
679 posts