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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 ## Each of the 25 balls in a certain box is either red, blue, tagged by: BTGmoderatorLU ##### This topic has 2 expert replies and 0 member replies ### Top Member ## Each of the 25 balls in a certain box is either red, blue, ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Source: GMAT Prep Each of the 25 balls in a certain box is either red, blue, or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it? 1) The probability that the ball will both be white and have an even number painted on it is 0. 2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2. The OA is E. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15103 messages Followed by: 1859 members Upvotes: 13060 GMAT Score: 790 BTGmoderatorLU wrote: Source: GMAT Prep Each of the 25 balls in a certain box is either red, blue, or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it? 1) The probability that the ball will both be white and have an even number painted on it is 0. 2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2. Let: W = the total number of white marbles. E = the total number of even marbles. WE = the total number of white even marbles. Statement 1: Thus, WE = 0. No way to determine the value of W or E. INSUFFICIENT. Statement 2: Implication: W-E = (0.2)(25) = 5. Case 1: W=10, E=5, WE=0 Here, P(W or E) = (10+5)/25 = 15/25 = 3/5. Case 2: W=11, E=6, WE=0 Here, P(W or E) = (11+6)/25 = 17/25. Since P(W or E) can be different values, INSUFFICIENT. Statements combined: Cases 1 and 2 satisfy both statements. Since P(W or E) can be different values, INSUFFICIENT. The correct answer is E. _________________ 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. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12655 messages Followed by: 1245 members Upvotes: 5254 GMAT Score: 770 BTGmoderatorLU wrote: Source: GMAT Prep Each of the 25 balls in a certain box is either red, blue, or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it? 1) The probability that the ball will both be white and have an even number painted on it is 0. 2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2. The OA is E. Target question: What is the value of P(white or even)? To solve this, we need P(A or B) = P(A) + P(B) - P(A & B) So, P(white or even) = P(white) + P(even) - P(white & even) Statement 1: P(white & even) = 0 We can add this to our probability equation to get: P(white or even) = P(white) + P(even) - 0 Still need P(white), and we need P(even) INSUFFICIENT Statement 2: P(white) - P(even)= 0.2 We have no idea about the sum of P(white) and P(even), and we don't know the value of P(white & even) INSUFFICIENT Statements 1 and 2 combined: Given P(white) - P(even)= 0.2 does not tell us the individual values of P(white) and P(even), and it doesn't tell us the value of P(white) + P(even). So, since we can't determine the value of P(white) + P(even) - P(white & even), the statements combined are not sufficient. Answer: E Cheers, Brent _________________ Brent Hanneson – Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months! • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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