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 →

Sets Problem

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 49
Joined: Thu May 19, 2011 9:20 pm
by sampath » Wed Aug 17, 2011 2:36 am
The Mathematics Club in a school held an open house on three afternoons. 115, 75 and 110 students
attended on the first, second and third afternoons respectively. 30 attended only on the first day, 35 on the first and second days. 70 attended the first and the third days and 35 attended on the second and third days. How many attended on all the three days?
(A) 15 (B) 25 (C) 21 (D) 20 (E) 30
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 34
Joined: Mon Nov 15, 2010 12:12 pm
Thanked: 2 times

by rppala90 » Wed Aug 17, 2011 5:34 am
n(F) = n(F only) + n(F&S) + n(F&T) - n(F&S&T)
F --> First day.
S --> Second day.
T --> Third day.

[spoiler]115 = 30 + 35 + 70 - n(F&S&T)
n(F&S&T) = 135 - 115 = 20
Hence (D)[/spoiler]
I think info about n(S&T), n(S) and n(T) are not needed to solve this question.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 102
Joined: Thu Jul 21, 2011 2:22 amFollowed by: 1 member
Location: Lahore, Pakistan
Thanked: 4 times

by chufus » Wed Aug 17, 2011 5:59 am
rppala90 wrote:n(F) = n(F only) + n(F&S) + n(F&T) - n(F&S&T)
F --> First day.
S --> Second day.
T --> Third day.

[spoiler]115 = 30 + 35 + 70 - n(F&S&T)
n(F&S&T) = 135 - 115 = 20
Hence (D)[/spoiler]
I think info about n(S&T), n(S) and n(T) are not needed to solve this question.
Everything seems correct to your approach. Wonder why the other info was mentioned in the question. Doesn't seem like a GMAT question !
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 9
Joined: Thu Aug 04, 2011 12:07 am

by krishna8143 » Wed Aug 17, 2011 11:05 pm
ans is D 20
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 143
Joined: Sat Nov 06, 2010 9:06 pmFollowed by: 1 member
Thanked: 10 times

by edvhou812 » Wed Aug 17, 2011 11:27 pm
chufus wrote:
rppala90 wrote:n(F) = n(F only) + n(F&S) + n(F&T) - n(F&S&T)
F --> First day.
S --> Second day.
T --> Third day.

[spoiler]115 = 30 + 35 + 70 - n(F&S&T)
n(F&S&T) = 135 - 115 = 20
Hence (D)[/spoiler]
I think info about n(S&T), n(S) and n(T) are not needed to solve this question.
Everything seems correct to your approach. Wonder why the other info was mentioned in the question. Doesn't seem like a GMAT question !
This is a GMAT question.
I don't know what to say, really. Three minutes to the biggest battle of our professional lives. You find out life's this game of inches, so is football. Because in either game - life or football - the margin for error is so small. I mean, one half a step too late or too early and you don't quite make it. One half second too slow, too fast and you don't quite catch it. I'll tell you this, in any fight it's the guy whose willing to die whose gonna win that inch. That's football guys, that's all it is. Now, what are you gonna do?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1