Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

It is currently 21 Jul 2019, 20:34

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.

Close

Request Expert Reply

Confirm Cancel

Rhoda tosses a coin 5 times. Find the probability of getting exactly 4

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Manager
Manager
avatar
B
Joined: 23 Nov 2014
Posts: 60
Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post Updated on: 24 Aug 2017, 23:58
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

71% (00:59) correct 29% (00:52) wrong based on 65 sessions

HideShow timer Statistics


Rhoda tosses a coin 5 times. Find the probability of getting exactly 4 heads.

A. 1/32
B. 1/16
C. 3/32
D. 1/8
E. 5/32


Answer: 5/32


I fail to understand why have we multiplied by (5).

Originally posted by ruchi857 on 17 May 2016, 04:21.
Last edited by Bunuel on 24 Aug 2017, 23:58, edited 2 times in total.
Edited the question.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 56307
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post 17 May 2016, 04:30
Intern
Intern
avatar
Joined: 17 Jan 2016
Posts: 3
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post 21 May 2016, 10:54
Would be glad if I get a more elaborate explanation to this problem.
Intern
Intern
avatar
B
Joined: 10 Jul 2016
Posts: 49
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post 10 Jul 2016, 05:59
1
Please note that the coin problems are very similar to alphabet problems and can be solved in the same way.

Exactly 4 heads out of 5 would be: HHHHT, HHTHH, or many other combinations.

therefore, no. of possible combinations are 5!/4!*1! = 5

Probability = 5/2^5 = 5/32
Manager
Manager
avatar
S
Joined: 13 Dec 2013
Posts: 150
Location: United States (NY)
Concentration: General Management, International Business
Schools: Cambridge"19 (A)
GMAT 1: 710 Q46 V41
GMAT 2: 720 Q48 V40
GPA: 4
WE: Consulting (Consulting)
Reviews Badge
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post 08 Dec 2016, 00:39
To get 4 heads from 5 tosses there must be 4H and 1T. The probability of getting 4H and then 1T is 1/(2^5).
However, there are 5 ways to arrange 4H and 1T in 5 tosses. This is found using combinations nCr: 5!/(4!)(1!).
Multiplying the probability by the number of arrangements = 5/32.
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2822
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4  [#permalink]

Show Tags

New post 14 Jul 2018, 19:27
ruchi857 wrote:
Rhoda tosses a coin 5 times. Find the probability of getting exactly 4 heads.

A. 1/32
B. 1/16
C. 3/32
D. 1/8
E. 5/32


The probability of H-H-H-H-T in this order is (½)^4 (½) = 1/32. However, the 4 heads and 1 tail can be arranged in 5!/4! = 5 ways. Therefore, the probability of getting 4 heads and 1 tail is 5 x 1/32 = 5/32.

Answer: E
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMAT Club Bot
Re: Rhoda tosses a coin 5 times. Find the probability of getting exactly 4   [#permalink] 14 Jul 2018, 19:27
Display posts from previous: Sort by

Rhoda tosses a coin 5 times. Find the probability of getting exactly 4

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne