It is currently 14 Dec 2017, 18:48

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the probability of getting a six on either the first

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Intern
Intern
avatar
Joined: 28 Nov 2005
Posts: 33

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

What is the probability of getting a six on either the first [#permalink]

Show Tags

New post 29 Sep 2007, 02:37
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

What is the probability of getting a six on either the first or second toss of a normal six-sided die ?
A) 1/36
B) 1/18
C) 1/6
D) 11/36
E) 1/3

Please explain.
I've got 2 methods to solve this, but I don't get the same result with the 2.
Thanks.

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

VP
VP
User avatar
Joined: 08 Jun 2005
Posts: 1141

Kudos [?]: 257 [0], given: 0

 [#permalink]

Show Tags

New post 29 Sep 2007, 02:42
1
This post was
BOOKMARKED
getting six on dice roll ---> 1/6

5/6*1/6 ---> second toss
1/6*5/6 ---> first toss
1/6*1/6 ---> both

5/36+5/36+1/36 = 11/36

:)

Kudos [?]: 257 [0], given: 0

Intern
Intern
avatar
Joined: 28 Nov 2005
Posts: 33

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

 [#permalink]

Show Tags

New post 29 Sep 2007, 07:06
Thanks for you quick reply KillerSquirrel !

My mistake came from forgetting to take into account the "BOTH" as belonging to either 1st OR 2nd ?

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

SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1543

Kudos [?]: 189 [0], given: 2

 [#permalink]

Show Tags

New post 29 Sep 2007, 07:18
wow i was totally off the ball.

To me, I just thought of it like this:

prob of 6 on roll 1 = 1/6

prob of 6 on roll 2 = 1/6


therefore, prob or 6 on 1st or 2nd roll = 1/6 + 1/6 = 1/3

Where did my logic go wrong ?

Kudos [?]: 189 [0], given: 2

VP
VP
User avatar
Joined: 08 Jun 2005
Posts: 1141

Kudos [?]: 257 [0], given: 0

 [#permalink]

Show Tags

New post 29 Sep 2007, 07:24
1
This post was
BOOKMARKED
pmenon wrote:
wow i was totally off the ball.

To me, I just thought of it like this:

prob of 6 on roll 1 = 1/6

prob of 6 on roll 2 = 1/6


therefore, prob or 6 on 1st or 2nd roll = 1/6 + 1/6 = 1/3

Where did my logic go wrong ?


Since you have one outcome where you get 6:6 then you need to remove this duplicate of six's (you counted it once in the first roll then in the second roll) hence 1/6+1/6-1/36 = 6/36+6/36-1/36 = 11/36.

:)

Kudos [?]: 257 [0], given: 0

SVP
SVP
avatar
Joined: 28 Dec 2005
Posts: 1543

Kudos [?]: 189 [0], given: 2

 [#permalink]

Show Tags

New post 29 Sep 2007, 07:37
Ah i think i see it now:

we have to subtract the probability that we get 6s on BOTH rolls, which would be 1/6*1/6=1/36

So , if the answer were just 1/6 + 1/6, how would the question need to be worded differently ?

Kudos [?]: 189 [0], given: 2

Intern
Intern
avatar
Joined: 28 Nov 2005
Posts: 33

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

 [#permalink]

Show Tags

New post 29 Sep 2007, 08:05
pmenon wrote:
Ah i think i see it now:

we have to subtract the probability that we get 6s on BOTH rolls, which would be 1/6*1/6=1/36

So , if the answer were just 1/6 + 1/6, how would the question need to be worded differently ?


I guess it would be something like : "What is the probability to guet 6 ONLY at the first or ONLY at the second roll ?"

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

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 14843

Kudos [?]: 287 [0], given: 0

Premium Member
Re: What is the probability of getting a six on either the first [#permalink]

Show Tags

New post 29 Nov 2017, 00:41
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Kudos [?]: 287 [0], given: 0

Re: What is the probability of getting a six on either the first   [#permalink] 29 Nov 2017, 00:41
Display posts from previous: Sort by

What is the probability of getting a six on either the first

  post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderator: chetan2u



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

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

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®.