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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 ## In the graduating class of a certain college, 48 percent of ##### This topic has 2 expert replies and 0 member replies ### Top Member ## In the graduating class of a certain college, 48 percent of ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult In the graduating class of a certain college, 48 percent of the students are male and 52 percent are female. In this class 40 percent of the male and 20 percent of the female students are 25 years old or older. If one student in the class is randomly selected, approximately what is the probability that he or she will be less than 25 years old? A. 0.9 B. 0.7 C. 0.45 D. 0.3 E. 0.25 OA B Source: GMAT Prep ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 13001 messages Followed by: 1250 members Upvotes: 5254 GMAT Score: 770 Top Reply I thought I'd point out that Mitch's Double Matrix Method approach can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of students, and the two characteristics are: - male or female - younger than 25 or older than 25 This question type is VERY COMMON on the GMAT, so be sure to master the technique. To learn more about the Double Matrix Method, watch this video: http://www.gmatprepnow.com/module/gmat-word-problems?id=919 Once youâ€™re familiar with this technique, you can attempt these additional practice questions: Easy Problem Solving questions - http://www.beatthegmat.com/finance-majors-non-finance-majors-overlapping-set-question-t167425.html Medium Problem Solving questions - http://www.gmatprepnow.com/module/gmat-word-problems/video/920 - http://www.beatthegmat.com/posted-speed-limit-t272374.html - http://www.beatthegmat.com/motel-t271938.html - http://www.beatthegmat.com/of-the-applicants-passes-a-certain-test-15-t270255.html - http://www.beatthegmat.com/opening-night-and-late-patrons-t264869.html - http://www.beatthegmat.com/at-least-100-students-at-a-certain-high-school-study-japanes-t274669.html - http://www.beatthegmat.com/prblem-solving-t279424.html Difficult Problem Solving questions - http://www.gmatprepnow.com/module/gmat-word-problems/video/946 - http://www.beatthegmat.com/ratio-problem-t268339.html - http://www.beatthegmat.com/overlapping-sets-question-t265223.html - http://www.beatthegmat.com/fractions-t264254.html - http://www.beatthegmat.com/overlapping-sets-t264092.html - http://www.beatthegmat.com/mba/2011/05/09/random-double-matrix-question-2 Easy Data Sufficiency questions - http://www.gmatprepnow.com/module/gmat-word-problems/video/943 - http://www.beatthegmat.com/for-what-percent-of-those-tested-for-a-certain-t270596.html - http://www.beatthegmat.com/ds-quest-t187706.html Medium Data Sufficiency questions - http://www.beatthegmat.com/sets-matrix-ds-t271914.html - http://www.beatthegmat.com/each-of-people-voted-once-in-an-election-x-t271375.html - http://www.beatthegmat.com/a-manufacturer-t270331.html - http://www.beatthegmat.com/in-costume-for-halloween-t269355.html - http://www.beatthegmat.com/mba/2011/05/05/random-double-matrix-question-1 Difficult Data Sufficiency questions - https://youtu.be/dsCeqF9Kbk8 - http://www.beatthegmat.com/double-set-matrix-question-t271423.html - https://youtu.be/dOZ9KM1m5Hs - http://www.beatthegmat.com/sets-t269449.html - http://www.beatthegmat.com/mba/2011/05/16/random-double-matrix-question-3 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: 15362 messages Followed by: 1866 members Upvotes: 13060 GMAT Score: 790 Top Reply BTGmoderatorDC wrote: In the graduating class of a certain college, 48 percent of the students are male and 52 percent are female. In this class 40 percent of the male and 20 percent of the female students are 25 years old or older. If one student in the class is randomly selected, approximately what is the probability that he or she will be less than 25 years old? A. 0.9 B. 0.7 C. 0.45 D. 0.3 E. 0.25 Every student is EITHER male OR female. Every student is EITER older OR younger. For an EITHER/OR problem, use a DOUBLE MATRIX to organize the data: _______________M______F_______Total older: younger: total: Let total students = 100: _______________M______F_______Total older: younger: total:__________________________100 48% males, 52% females. Since we're looking for an approximation, let's say that 50% are males and 50% are females: _________________M______F_______Total older: younger: total:__________50_____50________100 40% of the males and 20% of the females are 25 and older: _________________M______F_______Total older:__________20_____10_______ younger: total:__________50_____50________100 Complete the matrix: _________________M______F_______Total older:__________20_____10________30 younger:_______30_____40________70 total:__________50_____50________100 P(younger) = 70/100 = 0.7. The correct answer is B. _________________ 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 Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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