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 →

GMATPrep test 1 SD problem

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 37
Joined: Tue Jan 29, 2008 12:02 pm
by rainbownlife » Tue Jan 29, 2008 12:15 pm
please explain. Waht are all the SD formule one needs to remmeber.

thanx in advance !

If a sample data has mean = 20 and std deviation=3.0 , which of the following is more than 2.5 std deviation from mean.

12,13.5,17,23.5,26.5
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 49
Joined: Sun Jul 01, 2007 5:56 pm
Thanked: 3 times

by smushkas » Tue Jan 29, 2008 2:04 pm
Hey there,

This is very easy one. All you have to do is just ad/subtract SD to/from the mean. Before you have to multiply by the given number, which is 2.5 SD. Thus,
20 + (2.5 * 3) = 20 + 7.5 = 27.5
20 - (2.5 * 3) = 20 - 7.5 = 12.5.
Your data should be outside the range of 12.5 ~ 27.5. All the numbers lie in the range except 12, the answer must be [A].
Last edited by smushkas on Tue Jan 29, 2008 2:14 pm, edited 1 time in total.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members
Location: Toronto
Thanked: 1710 times
GMAT Score:800

Re: GMATPrep test 1 SD problem

by Stuart@KaplanGMAT » Tue Jan 29, 2008 2:09 pm
rainbownlife wrote:please explain. Waht are all the SD formule one needs to remmeber.

thanx in advance !

If a sample data has mean = 20 and std deviation=3.0 , which of the following is more than 2.5 std deviation from mean.

12,13.5,17,23.5,26.5
Smushka's explanation is 100% correct, I just want to add a strategic guessing tip for this question.

Since the question is asking us for the number outside of 2.5 SD, the only possible choices are the two extremes, (a) and (e) - so, even if you're stuck, you have a 50/50 shot at the question.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 37
Joined: Tue Jan 29, 2008 12:02 pm

by rainbownlife » Mon Feb 04, 2008 2:19 pm
great!
I just reviewed SD basics...and now this question makes sense :)
thanks for your replies !
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1