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 →

Formula for no. of items in a sets

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 amFollowed by: 10 members
Thanked: 20 times
GMAT Score:700
by prachich1987 » Fri Jan 21, 2011 6:39 am
True # of items = (total # in group 1) + (total # in group 2) + (total # in group 3) - (# in only groups 1/2) - (# in only groups 1/3) - (# in only groups 2/3) - 2(# in all 3 groups) + (# in no groups)


Can this formula be applied to ALL sets which contain three different item or it has some limitations?

Thanks !
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Legendary Member
Posts: 1578
Joined: Sun Dec 28, 2008 1:49 amFollowed by: 9 members
Thanked: 82 times
GMAT Score:720

by maihuna » Fri Jan 21, 2011 9:36 am
this is generic enough what limitation r u talking abt
Charged up again to beat the beast :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 1035
Joined: Fri Dec 17, 2010 11:13 amFollowed by: 365 members
Location: Los Angeles, CA
Thanked: 474 times

by VivianKerr » Sat Jan 22, 2011 6:59 pm
Hi there,

I'm also not quite clear on what you question is. This page has a nice list of set theory formulas with a Venn diagram so you can visualize it. It should help clarify: https://gmat-maths.blocked/2008/05/ ... mulas.html
Vivian Kerr
GMAT Rockstar, Tutor
https://www.GMATrockstar.com
https://www.yelp.com/biz/gmat-rockstar-los-angeles

Former Kaplan and Grockit instructor, freelance GMAT content creator, now offering affordable, effective, Skype-tutoring for the GMAT at $150/hr. Contact: [email protected]

Thank you for all the "thanks" and "follows"! :-)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 752
Joined: Sun Sep 12, 2010 2:47 amFollowed by: 10 members
Thanked: 20 times
GMAT Score:700

by prachich1987 » Sat Jan 22, 2011 10:21 pm
Thanks Vivian for providing the link
According to it ,

P(AuBuC) = P(A) + P(B) + P(C) - P(AnB) - P(AnC) - P(BnC) + P(AnBnC)

By True # of items, I mean actual no. of item in a set.
If there are three sets, then what is the formula for calculating actual no. of items
I found below formula from one of the posts on BTG.
But I think the below formula and the one I found on the link given by you are not same.

True # of items = (total # in group 1) + (total # in group 2) + (total # in group 3) - (# in only groups 1/2) - (# in only groups 1/3) - (# in only groups 2/3) - 2(# in all 3 groups) + (# in no groups)

Please help
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 21
Joined: Mon Feb 22, 2010 11:16 pm

by santoshs » Mon Jan 24, 2011 3:36 am
Here are some formulas that can be useful while dealing with 3 sets

Total number of people/Number of people in at least one set:
AuBuC = A + B + C - AnB - AnC - BnC + AnBnC

Number of people in exactly one set:
A + B + C - 2*AnB - 2*AnC - 2*BnC + 3*AnBnC

Number of people in exactly two of the sets:
AnB + AnC+ BnC - 3*AnBnC

Number of people in two or three sets:
AnB + AnC + BnC - 2*AnBnC

Number of people in exactly three of the sets =
AnBnC
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1