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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 ## Al can complte a particular job in 8 hours. Boris can... tagged by: BTGmoderatorLU ##### This topic has 1 expert reply and 0 member replies ### Top Member ## Al can complte a particular job in 8 hours. Boris can... Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job 2 hours, how long, in hours, would it take Al, working alone, to finish the job? A. 0.8 B. 3.0 C. 6.8 D. 8.0 E. 8.8 The OA is C. I'm really confused by this PS question. Experts, any suggestion about how to solve it? Thanks in advance. ### GMAT/MBA Expert Senior | Next Rank: 100 Posts Joined 16 Dec 2014 Posted: 94 messages Followed by: 4 members Upvotes: 2 GMAT Score: 770 Top Reply LUANDATO wrote: Al can complete a particular job in 8 hours. Boris can complete the same job in 5 hours. Cody can complete a second job, which requires twice as much work as the first, in 8 hours. If all three people work together on the larger job 2 hours, how long, in hours, would it take Al, working alone, to finish the job? A. 0.8 B. 3.0 C. 6.8 D. 8.0 E. 8.8 The OA is C. I'm really confused by this PS question. Experts, any suggestion about how to solve it? Thanks in advance. Job 1 rates: Al: 1/8 job per hour Boris: 1/5 job per hour Cody: 1/4 job per hour (we know this because Cody can do a job that is twice as much work in 8 hours, thus he must be able to do Job 1 in 4 hours) Job 2 rates (we know that Job 2 takes twice as long as Job 1): Al: 1/16 job per hour Boris: 1/10 job per hour Cody: 1/8 job per hour What is the larger job? This is Job 2 (it takes twice as long). If Al, Boris and Cody work together for two hours on Job 2, how much is done? Well that is 2(1/16) + 2(1/10) + 2(1/8) = 1/8 + 1/5 + 1/4 = 5/40 + 8/40 + 10/40 = 23/40 Thus, 17/40 of the job remains to be completed after two hours. It will take Al 16 hours to do a full Job 2 so it will take him 16*(17/40) to do the remainder. 16*(17/40) = 4*17/10 = 68/10 = 6.8 Answer is C. • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 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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