Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
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.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 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
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
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
GMATOnDemandStart 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 563 reviewsTarget Test Prep

the probability of revealing the secret message

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 48
Joined: Wed Aug 27, 2008 9:58 am
by nh8404052006 » Sun Dec 28, 2008 2:32 pm
Three persons try to decode a secret message independently. Their probabilities of successfully decoding are 1/5, 1/4 and 1/3. What is the probability that the secret message will be revealed?
Top
Join the discussion
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16206
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Sun Dec 28, 2008 2:47 pm
Three persons try to decode a secret message independently. Their probabilities of successfully decoding are 1/5, 1/4 and 1/3. What is the probability that the secret message will be revealed?
The question is asking what is P(at least one person decodes the message)
This probability equals 1 - P(no one decodes the message)

No one decoding the message means that the first person didn't decode the message AND the second person didn't decode the message AND the thrid person didn't decode the message.

The probability that all three fail to decode the message is 4/5 x 3/4 x 2/3 = 2/5

So, P(at least one person decodes the message) = 1-2/5 = 3/5
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Senior | Next Rank: 100 Posts
Posts: 37
Joined: Wed Sep 17, 2008 8:17 pm
Location: India
Thanked: 4 times

Re: the probability of revealing the secret message

by Sachindh » Sun Dec 28, 2008 8:15 pm
nh8404052006 wrote:Three persons try to decode a secret message independently. Their probabilities of successfully decoding are 1/5, 1/4 and 1/3. What is the probability that the secret message will be revealed?
The probability that no one has been successful in revealing = 4/5*3/4*2/3=2/5

Therefore answer will be 1-2/5 = 3/5
Top
Join the discussion