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

It is currently 02 Sep 2014, 13:38

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

On three consecutive flips of a coin, what is the probabilit

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 30 Jun 2012
Posts: 84
Location: United States
GMAT 1: 510 Q34 V28
GMAT 2: 580 Q35 V35
GMAT 3: 640 Q34 V44
GMAT 4: 690 Q43 V42
GPA: 3.61
WE: Education (Education)
Followers: 7

Kudos [?]: 82 [0], given: 16

On three consecutive flips of a coin, what is the probabilit [#permalink] New post 09 Jul 2013, 13:44
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

70% (01:24) correct 30% (00:23) wrong based on 61 sessions
On three consecutive flips of a coin, what is the probability that all three produce the same result?

(A) 1/16
(B) 1/8
(C) 1/4
(D) 3/8
(E) 1/2

[Reveal] Spoiler:
I came up with (1/2)*(1/2)*(1/2) =1/8

However, the explanation states that the answer is 1/4.

On the Total GMAT book, I had the following question: If a fair coin is flipped three times, what is the probability that it will be heads all three times?

There the answer given is 1/8, which is what I came up with.

Am I missing something? I do not see any distinction between these two questions.
[Reveal] Spoiler: OA

Last edited by Bunuel on 09 Jul 2013, 13:48, edited 1 time in total.
Edited the question and added the answer choices.
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 25253
Followers: 3433

Kudos [?]: 25284 [0], given: 2702

Re: On three consecutive flips of a coin, what is the probabilit [#permalink] New post 09 Jul 2013, 13:49
Expert's post
josemnz83 wrote:
On three consecutive flips of a coin, what is the probability that all three produce the same result?

(A) 1/16
(B) 1/8
(C) 1/4
(D) 3/8
(E) 1/2

[Reveal] Spoiler:
I came up with (1/2)*(1/2)*(1/2) =1/8

However, the explanation states that the answer is 1/4.

On the Total GMAT book, I had the following question: If a fair coin is flipped three times, what is the probability that it will be heads all three times?

There the answer given is 1/8, which is what I came up with.

Am I missing something? I do not see any distinction between these two questions.


TTT case --> P = (1/2)^3 = 1/8.
HHH case --> P = (1/2)^3 = 1/8.

P(TTT or HHH) = 1/8 + 1/8 = 1/4.

Answer: C.
_________________

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
avatar
Joined: 29 Jun 2013
Posts: 1
Followers: 0

Kudos [?]: 0 [0], given: 5

Re: On three consecutive flips of a coin, what is the probabilit [#permalink] New post 04 Aug 2013, 14:37
Why isn't "B" the answer?
1 KUDOS received
Director
Director
User avatar
Joined: 14 Dec 2012
Posts: 837
Location: India
Concentration: Finance, Real Estate
GMAT 1: 640 Q49 V29
GMAT 2: 670 Q50 V29
GMAT 3: 620 Q49 V26
GMAT 4: 700 Q50 V34
GPA: 3.6
Followers: 37

Kudos [?]: 570 [1] , given: 197

GMAT ToolKit User
Re: On three consecutive flips of a coin, what is the probabilit [#permalink] New post 04 Aug 2013, 14:44
1
This post received
KUDOS
fatimaba wrote:
Why isn't "B" the answer?


probability for head = 1/2
similarly probability for tails = 1/2

case 1: all 3 times = head
in that case
probability = 1/2*1/2*1/2 = 1/8

case 2 : all tails then again probability will be 1/8

so total probability will be 1/8+1/8 = 1/4

hope it helps
_________________

When you want to succeed as bad as you want to breathe ...then you will be successfull....

GIVE VALUE TO OFFICIAL QUESTIONS...



GMAT RCs VOCABULARY LIST: vocabulary-list-for-gmat-reading-comprehension-155228.html
learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmat- ... assessment
: http://www.youtube.com/watch?v=APt9ITygGss

Re: On three consecutive flips of a coin, what is the probabilit   [#permalink] 04 Aug 2013, 14:44
    Similar topics Author Replies Last post
Similar
Topics:
Coin is flipped monirjewel 1 20 Oct 2010, 05:41
1) What is the probability, when flipping a coin 6 times, of bmwhype2 1 12 Dec 2007, 05:22
3 a fair 2-sided coin is flipped 6 times. what is the bmwhype2 3 18 May 2007, 20:56
Kaplan Problem Susan flipped a fair coin N times. what minhthel 1 11 Jul 2006, 08:45
1 Kevin flips a coin four times. WHat is the probability the faisalt 11 18 Nov 2005, 04:11
Display posts from previous: Sort by

On three consecutive flips of a coin, what is the probabilit

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.