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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## What is the probability that the sum of two dice will yield tagged by: AAPL ##### This topic has 2 expert replies and 1 member reply ### Top Member ## What is the probability that the sum of two dice will yield ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Manhattan Prep What is the probability that the sum of two dice will yield a 7, and then when both are thrown again, their sum will again yield a 7? assume that each die has 6 sides with faces numbered 1 to 6. A. $$1/144$$ B. $$1/36$$ C. $$1/12$$ D. $$1/6$$ E. $$1/3$$ OA B ### Top Member Legendary Member Joined 02 Mar 2018 Posted: 1171 messages Followed by: 2 members Total number of ways in which 2 dice can be thrown = 6 * 6 = 36 The combination that will yield a sum of 7 are; $$1+6$$ $$2+5$$ $$3+4$$ $$4+3$$ $$5+2$$ $$6+1$$ All the 6 different combinations probability of rolling a 7 is 6/36 or 1/6. To find the probability of this happening twice in a row => $$\frac{1}{6}\cdot\frac{1}{6}=\frac{1}{36}\ \ \ \ \ \ Answer=option\ B$$ ### GMAT/MBA Expert GMAT Instructor Joined 02 Jun 2008 Posted: 2525 messages Followed by: 352 members Upvotes: 1090 GMAT Score: 780 If you roll one die, you can always make a sum of 7 if you get the perfect roll on the second die. There's a 1/6 chance you roll the perfect number, so that's the probability of getting a sum of 7. The probability we do that twice in a row is (1/6)(1/6) = 1/36. You could get down to A or B instantly by noticing that the answer needs to be the square of some very simple fraction of integers. _________________ If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2950 messages Followed by: 19 members Upvotes: 43 AAPL wrote: Manhattan Prep What is the probability that the sum of two dice will yield a 7, and then when both are thrown again, their sum will again yield a 7? assume that each die has 6 sides with faces numbered 1 to 6. A. $$1/144$$ B. $$1/36$$ C. $$1/12$$ D. $$1/6$$ E. $$1/3$$ OA B Since there are a total of 36 outcomes, and 6 of them yield a sum of 7 (notice that these 6 outcomes are: {1, 6}, {2, 5}, {3, 4}, {4, 3}, {5, 2} and {6, 1}), the probability that the two numbers on the dice yield a sum of 7 is 6/36 = 1/6. The probability that their sum will again yield a 7 is 1/6. Therefore, the probability that the two dice will yield a sum of 7 twice is 1/6 x 1/6 = 1/36. Answer: B _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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