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
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
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 Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget 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.

Probalility

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 85
Joined: Mon Nov 12, 2012 11:12 amFollowed by: 2 members
Thanked: 8 times
by Anindya Madhudor » Sun Sep 08, 2013 7:32 am
The governor has decided to pardon one of the three prisoners (A, B, C) who are on death row and informs the prison warden about his decision. Prisoner A asks the warden which prisoner will be pardoned and the warden informs him that B is to be executed. What is the updated probability of A being pardoned?

A. 1/2
B. 1/3
C. 1/6
D. 2/3
E. 1/4

OA: B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Sun Sep 08, 2013 8:06 am
Anindya Madhudor wrote:The governor has decided to pardon one of the three prisoners (A, B, C) who are on death row and informs the prison warden about his decision. Prisoner A asks the warden which prisoner will be pardoned and the warden informs him that B is to be executed. What is the updated probability of A being pardoned?

A. 1/2
B. 1/3
C. 1/6
D. 2/3
E. 1/4

OA: B
This is a variation of the Monty Hall problem, a somewhat famous question that appeared in 1975. The original question is:
Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice?

Answer: [spoiler]Yes, you should switch your choice. If you switch your choice to door #2, the probability is 2/3 that you'll win the car. If you stay with door #1, the probability is 1/3 that you'll win the car. [/spoiler]

More here: https://en.wikipedia.org/wiki/Monty_Hall_problem

If you read the Wikipedia article, you'll see that the question stumped a LOT of people, including several mathematicians. As such, I don't think this question is within the scope of the GMAT.

Yes, I know a lot of people will argue that it only makes sense that, if the probability of prisoner A getting pardoned is 1/3 BEFORE asking the warden, then the probability should remain 1/3 AFTER the warden reveals that prisoner B is NOT pardoned. However, I'm not certain that this conclusion is as obvious as some people might believe.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members
Location: Palo Alto, CA
Thanked: 2867 times
GMAT Score:800

by [email protected] » Sun Sep 08, 2013 1:10 pm
Hi Anindya Madhudor,

Brent is absolutely correct; the GMAT will NEVER ask you a probability question phrased in this way. Furthermore, any GMAT book/resource that would offer this as a viable sample question is probably not the best material to be studying from.

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1