BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

SD

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 1578
Joined: Sun Dec 28, 2008 1:49 amFollowed by: 9 members
Thanked: 82 times
GMAT Score:720
by maihuna » Tue Mar 15, 2011 12:20 pm
In the period between 1975 and 1985, the population of each of
the Â…ve major cities in country C increased by at least 10,000
people. If the standard deviation of the populations in 1975
was 35,000 people, what was the standard deviation of the
populations in 1985?
(1) The total increase in population of the Â…ve cities from
1975 to 1985 was 220,000 people.
(2) Each of the Â…ve cities increased in population by 12% in
the period between 1975 and 1985.
Charged up again to beat the beast :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 582
Joined: Tue Mar 08, 2011 12:48 amFollowed by: 6 members
Thanked: 61 times
GMAT Score:740

by force5 » Tue Mar 15, 2011 1:44 pm
MY Take is B , what's the OA?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pmFollowed by: 10 members
Thanked: 127 times

by Night reader » Tue Mar 15, 2011 3:12 pm
hi maihuna, an excellent question testing SD concept which follows:

New Mean or New SD = Old Mean or old SD * (1+% increase/decrease)

as we see st(1) is Not Sufficient, we are given only total increase
st(2) is also Sufficient, we are given the percentage increase and the question can be answered SD in 1985 = SD in 1975 * 1.12

IOM B
maihuna wrote:In the period between 1975 and 1985, the population of each of
the Â…ve major cities in country C increased by at least 10,000
people. If the standard deviation of the populations in 1975
was 35,000 people, what was the standard deviation of the
populations in 1985?
(1) The total increase in population of the Â…ve cities from
1975 to 1985 was 220,000 people.
(2) Each of the Â…ve cities increased in population by 12% in
the period between 1975 and 1985.
Last edited by Night reader on Thu Mar 17, 2011 5:13 am, edited 1 time in total.
My knowledge frontiers came to evolve the GMATPill's methods - the credited study means to boost the Verbal competence. I really like their videos, especially for RC, CR and SC. You do check their study methods at https://www.gmatpill.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 582
Joined: Tue Mar 08, 2011 12:48 amFollowed by: 6 members
Thanked: 61 times
GMAT Score:740

by force5 » Wed Mar 16, 2011 11:12 am
Maihuna can you post the OA please.......
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 61
Joined: Sun Mar 13, 2011 12:34 pm
Thanked: 1 times

by luiscarlos59 » Wed Mar 16, 2011 9:47 pm
I go with B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 423
Joined: Fri Jun 11, 2010 7:59 amFollowed by: 2 members
Location: Seattle, WA
Thanked: 86 times

by srcc25anu » Thu Mar 17, 2011 1:16 am
i think it should be B
since each of the 5 cities' population is growing by 12%, new sd = old sd * 1.12 or 35000*1.12
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 574
Joined: Sat Oct 31, 2009 1:47 pmFollowed by: 5 members
Location: USA
Thanked: 29 times

by Target2009 » Thu Mar 17, 2011 11:09 am
one more B
Regards
Abhishek
------------------------------
MasterGmat Student
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 1578
Joined: Sun Dec 28, 2008 1:49 amFollowed by: 9 members
Thanked: 82 times
GMAT Score:720

by maihuna » Fri Mar 18, 2011 6:35 am
OA Is B
force5 wrote:Maihuna can you post the OA please.......
Charged up again to beat the beast :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1