Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 44423

When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
09 Mar 2016, 13:04
Question Stats:
63% (00:44) correct 38% (00:52) wrong based on 136 sessions
HideShow timer Statistics



Intern
Joined: 12 Dec 2015
Posts: 18

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
09 Mar 2016, 14:06
1
This post received KUDOS
We have 8 outcomes that satisfy the question:
13 24 31 or 35 42 or 46 53 64.
For the first, second, fifth and sixth pairs the probability is (1/6*1/6)*4= 4/36. For fifth and sixth pairs probability is (1/6*2/6)*2=4/36, and the sum of all possibilities is 4/36+4/36=8/36=2/9
I think the answer is B



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11316
Location: United States (CA)
GRE 1: 340 Q170 V170

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
10 Mar 2016, 21:36
Hi AlexIV, Your work here is perfect, but it looks like you did a bunch of 'extra' math that wasn't necessary. When you roll two 6sided dice, there are (6)(6) = 36 possible outcomes. Once you listed the 8 options that 'fit' what the question was looking for, all you had to do was reduce the fraction: 8/36 = 2/9 Final Answer: GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



Intern
Joined: 06 Feb 2016
Posts: 1

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
28 Mar 2016, 05:59
1
This post received KUDOS
I found it easiest to make a quick chart, it took about 1 min
If the top horizontal row is the first die and the first vertical row the second die then, the difference between the two is the result in the number chart. I just counted the 2s to avoid missing any and then since it is 6x6 for all possible outcomes, then 8/36 is the answer. Hence 2/9
 123456 1 012345 2 101234 3 210123 4 421012 5 532101 6 643210



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11316
Location: United States (CA)
GRE 1: 340 Q170 V170

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
28 Mar 2016, 11:07
Hi cecammiade, That type of 'brute force' approach is perfect for certain types of questions on Test Day. As you've pointed out, it didn't take much time or effort to do the work and THAT is something to keep in mind as you're working through the entire GMAT. Most GMAT questions can be solve in a variety of ways, so sometimes you just have to put the pen on the pad and quickly 'map out' the solution. Your willingness to think in those terms likely means that you have a high potential to score well on Test Day. GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



SVP
Joined: 08 Jul 2010
Posts: 2017
Location: India
GMAT: INSIGHT
WE: Education (Education)

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
29 Mar 2016, 01:42
Bunuel wrote: When two dice are rolled, what is the probability that the difference between the two numbers is 2?
(A) 1/9 (B) 2/9 (C) 1/3 (D) 2/3 (E) None of the above Total Outcomes = 6*6 = 36 Favorable outcomes = {1, 3}, {2, 4}, {3, 5}, {3, 1}, {4, 6}, {4, 2}, {5, 3}, {6, 4} = 8 cases Probability = Favorable Outcomes / Total Outcomes = 8/36 = 2/9 Answer: Option B
_________________
Prosper!!! GMATinsight Bhoopendra Singh and Dr.Sushma Jha email: info@GMATinsight.com I Call us : +919999687183 / 9891333772 Online OneonOne Skype based classes and Classroom Coaching in South and West Delhi http://www.GMATinsight.com/testimonials.html
22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION



Director
Joined: 24 Nov 2015
Posts: 582
Location: United States (LA)

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
03 May 2016, 04:23
Probability = Favorable outcomes / Total outcomes Possible Favorable outcomes = (1,3) , (2,4) , (3,5) , (4,6) , (3,1) , (4,2) , (5,3) , (6,4) Number of possible outcomes = 8 Total outcomes = 6 * 6 = 36
Probability = \(\frac{8}{36}\) = \(\frac{2}{9}\) correct answer  B



Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2166

Re: When two dice are rolled, what is the probability that the difference [#permalink]
Show Tags
26 Oct 2017, 15:25
Bunuel wrote: When two dice are rolled, what is the probability that the difference between the two numbers is 2?
(A) 1/9 (B) 2/9 (C) 1/3 (D) 2/3 (E) None of the above There are a total of 6 x 6 = 36 possible outcomes when two dice are rolled. Of the 36 possible outcomes, there are 8 outcomes with a difference of 2: (1,3), (3,1), (2,4), (4,2), (3,5), (5,3), (4,6), (6,4). So, the probability of getting the difference of 2 is 8/36 = 2/9. Answer: B
_________________
Jeffery Miller
Head of GMAT Instruction
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions




Re: When two dice are rolled, what is the probability that the difference
[#permalink]
26 Oct 2017, 15:25






