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

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
Vote for Target Test Prep, Newsweek Readers’ Choice Awards 2026
NEWSWEEK READERS’ CHOICE 2026

BIG NEWS! Target Test Prep has been nominated, and they’d love your vote!

TTP has worked incredibly hard to build the best test prep experience possible, and winning Newsweek’s 2026 Readers’ Choice Award for Best Test Prep would mean a lot to them. If TTP has helped you, they’d be incredibly grateful for your vote. You can vote once each day through September 9.

Vote for TTP
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

most confusing number property problem!

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 122
Joined: Mon Sep 22, 2008 5:11 pm
Thanked: 1 times
by abcdefg » Sat Jun 13, 2009 11:27 am
This is found in p. 120 of the GMAT Review OG 11th edition.
P(A) = 0.23 and P(C) = 0.85

The book then jumps to the following conclusions.
1. We cannot determine P(A or C) and P(A and C)
2. 0.85 < P (A or C) < 1 [all inclusive]
3. 0.08 < P (A and C) < 0.23 [ all inclusive]

Can someone please explain to me how the book arrived at these conclusions?

The book says that P(A) + P(C) = 1.08, which is greater than 1, and therefore cannot equal P(A or C). Why is that?
The book then says following that P (A and C) > 0.08 inclusive.

Anyways just very confused. Would appreciate any help. Thanks.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Quantitative Reasoning |
Master | Next Rank: 500 Posts
Posts: 103
Joined: Mon May 18, 2009 9:47 am
Thanked: 19 times

by raleigh » Sat Jun 13, 2009 12:37 pm
Can you state the actual problem? I have OG 12th edition so I can't see the problem.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 49
Joined: Tue Jun 16, 2009 8:20 pm
Thanked: 5 times

by zenithexe » Sun Jun 21, 2009 4:04 am
Hey, I know it's old post, but I got OG 11th so here I go

this is not a problem question, he is confused about the explanation given regarding the "Discrete probability."
First part of his post is not really relevant, to boil it down, his question would be
Q1:Why is Event A and C cannot be mutually exclusive when P(A)+P(C)>1?

Q2:Why is P(A&C) >= 0.08 when P(A)+P(C)=1.08?


To explain, think of venn diagram with two circles. The area/probability of two circles minus the overlapping part must add up to less than 1.
Mutually exclusive means that two circles cannot overlap, hence, probability of A plus B must be less than 1. So, A and C cannot be mutually exclusive.

To make to the two circle's area to be less than 1, it has to overlap by 0.08 or grater to make the circle fit in a box with area of 1. If the overlap is grater than 0.08, then it will leave empty space in the box (probability of both events not occurring)

Look here for visualization: https://cs.uni.edu/~campbell/stat/venn.html
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1