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 →

password

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 60
Joined: Sat Jul 16, 2011 11:56 pmFollowed by: 1 member
Location: hyderabad
Thanked: 2 times
by naveen451 » Thu Jul 28, 2011 11:06 pm
5. A password of a computer used five digits where they are from 0 and 9. What is the probability that the password solely consists of prime numbers and zero?
A 1/32
B 1/16
C 1/8
D 2/5
E ½
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Senior | Next Rank: 100 Posts
Posts: 54
Joined: Sun Nov 29, 2009 7:11 pm
Location: Bangalore
Thanked: 4 times

by abhisays » Thu Jul 28, 2011 11:19 pm
The answer is A


prob. = fav. no. of cases / total no. of cases.

fav. no. of cases = 5*5*5*5*5

total no. of cases = 10*10*10*10*10

hence prob. = 5*5*5*5*5/10*10*10*10*10 = 1/32

logic is...

for favorable no. of cases.

we have to make a password from 5 digits (0,2,3,5,7) means five digits are there to fill five spots.. repetition is allowed as password can be 00000 or 22233.. so first place in five digit password can be filled with 5 options.. similarly for second.. third and so on..

apply this logic for total no. of cases.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 144
Joined: Sun Aug 29, 2010 9:17 amFollowed by: 4 members
Thanked: 40 times
GMAT Score:760

by jaymw » Fri Jul 29, 2011 2:19 am
5. A password of a computer used five digits where they are from 0 and 9. What is the probability that the password solely consists of prime numbers and zero?
A 1/32
B 1/16
C 1/8
D 2/5
E ½
The digits: 0,2,3,5,7 fulfill the requirements of the password. The digits 1,4,6,8,9 do not.

Therefore, for the first digit of the password there is a 5/10 = 1/2 chance that it will fit the requirements.

Since repetition is allowed, the same is true for the remaining four digits of the password.

Hence:

(1/2)^5=1/32

The answer is A.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1