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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 ## If a child flips a coin five times in a row, what is the tagged by: AAPL ##### This topic has 2 expert replies and 0 member replies ### Top Member ## If a child flips a coin five times in a row, what is the ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Veritas Prep If a child flips a coin five times in a row, what is the probability that she will receive at least one head and one tail? A. 3/4 B. 11/12 C. 15/16 D. 31/32 E. 63/64 OA C ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12921 messages Followed by: 1248 members Upvotes: 5254 GMAT Score: 770 AAPL wrote: Veritas Prep If a child flips a coin five times in a row, what is the probability that she will receive at least one head and one tail? A. 3/4 B. 11/12 C. 15/16 D. 31/32 E. 63/64 OA C If a coin is flipped 5 times in a row, there are 32 possible outcomes (HHTTH, HTHTT, TTTTT, etc) How did we get 32? Well, there are 2 possible outcomes for the 1st coin flip, 2 possible outcomes for the 2nd coin flip, 2 outcomes for the 3rd flip, 2 outcomes for the 4th flip, and 2 outcomes for the 5th flip, By the Fundamental Counting Principle (FCP), the TOTAL number of outcomes when flipping 5 coins = (2)(2)(2)(2)(2) = 32 Of course, among those 32 outcomes, there are some outcomes that DO NOT meeting the required condition that we receive at least one head and one tail There are EXACTLY 2 outcomes that DO NOT meet this required condition. They are: TTTTT and HHHHH So, the number of outcomes that DO meet the required condition = 32 - 2 = 30 So, P(child gets at least one head and one tail) = 30/32= 15/16 Answer: C Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2624 messages Followed by: 18 members Upvotes: 43 AAPL wrote: Veritas Prep If a child flips a coin five times in a row, what is the probability that she will receive at least one head and one tail? A. 3/4 B. 11/12 C. 15/16 D. 31/32 E. 63/64 Since each coin has two faces, head and tail, there are 2^5 = 32 different combinations when flipping a coin five times in a row. Of these 32 combinations, only two of them do not have at least one head and one tail. It occurs when all 5 flips turn out to be heads (HHHHH) or all 5 turn out the be tails (TTTTT). The other 30 combinations will have at least one head and one tail, so the probability is 30/32 = 15/16. Answer: C _________________ 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 • 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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