Find all School-related info fast with the new School-Specific MBA Forum

It is currently 21 Oct 2014, 22:28

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the probability of getting at least 2 heads in a row

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 26 Mar 2012
Posts: 10
Followers: 0

Kudos [?]: 0 [0], given: 11

What is the probability of getting at least 2 heads in a row [#permalink] New post 15 Apr 2012, 21:03
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
What is the probability of getting at least 2 heads in a row on three flips of a fair coin?

no answers are available, sorry
1 KUDOS received
Intern
Intern
User avatar
Joined: 17 Feb 2012
Posts: 22
Schools: LBS '14
Followers: 2

Kudos [?]: 16 [1] , given: 8

Re: probability [#permalink] New post 15 Apr 2012, 21:56
1
This post received
KUDOS
If we don't read the question attentively, we will be very likely to make the wrong calculations. In my opinion:
1/2 X 1/2 X 1 (it doesen't matter) +
+
1/2 (the probability of not getting a head after the first flip) X 1/2 (the probability of getting a head) X 1/2( the probability of getting a head again)
=
1/4 + 1/8 = 3/8
_________________

KUDOS needed URGENTLY. Thank you in advance and be ACTIVE!

Senior Manager
Senior Manager
avatar
Joined: 12 Mar 2012
Posts: 370
Concentration: Operations, Strategy
Followers: 2

Kudos [?]: 107 [0], given: 31

Re: probability [#permalink] New post 15 Apr 2012, 22:00
rovshan85 wrote:
what is the prob. of getting at least 2 heads in a row on three flips of a fair coin?

no answers are available, sorry


probability for HHT;

Total number of ways of arranging HHT keeping HH intact is 2!

probability = 2! * (1/2)^3

probability for HHH;

no of ways= 1

probability = (1/2)^3

hence required answer = 2! * (1/2)^3 + (1/2)^3
= 3* 1/8 = 3/8

Hope this helps...!!
_________________

Practice Practice and practice...!!

If my reply /analysis is helpful-->please press KUDOS
If there's a loophole in my analysis--> suggest measures to make it airtight.

Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23357
Followers: 3605

Kudos [?]: 28734 [1] , given: 2839

Re: What is the probability of getting at least 2 heads in a row [#permalink] New post 16 Apr 2012, 00:09
1
This post received
KUDOS
Expert's post
rovshan85 wrote:
What is the probability of getting at least 2 heads in a row on three flips of a fair coin?

no answers are available, sorry


The probability of at least 2 heads in a row on three flips is the sum of the probabilities of the following three cases: HHT, THH and HHH.

Now, each case has the probability of (\frac{1}{2})^3, so P=3*(\frac{1}{2})^3=\frac{3}{8}.

Hope it's clear.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
User avatar
Joined: 17 Feb 2012
Posts: 22
Schools: LBS '14
Followers: 2

Kudos [?]: 16 [0], given: 8

Re: What is the probability of getting at least 2 heads in a row [#permalink] New post 16 Apr 2012, 00:17
Banuel's explanation is again the simpliest and the steadiest against mistakes.
_________________

KUDOS needed URGENTLY. Thank you in advance and be ACTIVE!

Re: What is the probability of getting at least 2 heads in a row   [#permalink] 16 Apr 2012, 00:17
    Similar topics Author Replies Last post
Similar
Topics:
1 What is the probability of getting only one head in a single throw alphonsa 2 14 Sep 2014, 07:14
6 Experts publish their posts in the topic What is the probability of getting exactly three heads on JusTLucK04 2 21 Apr 2014, 20:52
What is the probability of getting exactly 13 heads out of OasisNYK 3 29 Jun 2007, 18:01
What is the probability of getting at most 1 Head mandy 1 09 Sep 2005, 00:42
What is the probability of getting at least one six in a Antmavel 4 13 Mar 2005, 18:10
Display posts from previous: Sort by

What is the probability of getting at least 2 heads in a row

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.