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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 ## From a group of 5 managers (Joon, Kendra, Lee, Marnie and ##### This topic has 3 expert replies and 0 member replies ### Top Member ## From a group of 5 managers (Joon, Kendra, Lee, Marnie and ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected? (A) 0.1 (B) 0.2 (C) 0.25 (D) 0.4 (E) 0.6 OA A Source: Manhattan Prep ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2801 messages Followed by: 18 members Upvotes: 43 Top Reply BTGmoderatorDC wrote: From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected? (A) 0.1 (B) 0.2 (C) 0.25 (D) 0.4 (E) 0.6 OA A Source: Manhattan Prep There are a total of 5C2 = 5!/(3! x 2!) = (5 x 4)/2 = 10 ways of choosing two people from a group of five people. Since the selection of Marnie and Noomi corresponds to one of these choices, the probability of this selection is 1/10 = 0.1. Answer: A _________________ 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 ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12989 messages Followed by: 1249 members Upvotes: 5254 GMAT Score: 770 Top Reply BTGmoderatorDC wrote: From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected? (A) 0.1 (B) 0.2 (C) 0.25 (D) 0.4 (E) 0.6 OA A Source: Manhattan Prep Our goal is to find P(M and N both selected) Method #1: P(M and N both selected) = P(one of them is selected 1st AND the other selected 2nd) = P(one of them is selected 1st) x P(the other selected 2nd) = (2/5)(1/4) = 1/10 = 0.1 Aside: P(one of them is selected 1st) = 2/5 because I'm allowing for either Marnie or Noomi to be selected first. Method #2: P(M and N both selected) = P(M selected 1st AND N selected 2nd OR N selected 1st AND M selected 2nd) = P(M selected 1st AND N selected 2nd) + P(N selected 1st AND M selected 2nd) = (1/5)(1/4) + (1/5)(1/4) = 1/20 + 1/20 = 1/10 = 0.1 Answer: A 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 May 2010 Posted: 15356 messages Followed by: 1864 members Upvotes: 13060 GMAT Score: 790 BTGmoderatorDC wrote: From a group of 5 managers (Joon, Kendra, Lee, Marnie and Noomi), 2 people are randomly selected to attend a conference in Las Vegas. What is the probability that Marnie and Noomi are both selected? (A) 0.1 (B) 0.2 (C) 0.25 (D) 0.4 (E) 0.6 Approach 1; P = (good pair)/(all possible pairs) Good pair = Marnie and Noomi = 1 option. All possible pairs = the number of ways to select 2 managers from 5 options = 5C2 = (5*4)/(2*1) = 10 options. Thus: P = 1/10 = 0.1 Approach 2: P(M or N is selected first) = 2/5. (Of the 5 managers, 2 are M or N.) P(M or N is selected second) = 1/4. (Of the 4 remaining managers, 1 will be M or N, since either M or N was selected first.) To combine these probabilities, we multiply: 2/5 * 1/4 = 1/10 = 0.1 The correct answer is A. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. • FREE GMAT Exam Know how you'd score today for$0

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