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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 ## Boat/Stream ##### This topic has 1 expert reply and 2 member replies ## Boat/Stream Q. A swimmer swims from point A against the current for 5 minutes and then swims backward with the current for next 5 minutes and comes to the point B. If AB = 100 meters, then the speed of the current in km/hr is? a. 0.06 b. 0.2 c. 0.6 d. 1 e. None of these Master | Next Rank: 500 Posts Joined 15 Oct 2009 Posted: 329 messages Upvotes: 27 Joy Shaha wrote: Q. A swimmer swims from point A against the current for 5 minutes and then swims backward with the current for next 5 minutes and comes to the point B. If AB = 100 meters, then the speed of the current in km/hr is? a. 0.06 b. 0.2 c. 0.6 d. 1 e. None of these Assume for simplicity that the swimmer swims at the same rate as the stream, call it X km/hr. Therefore, swimming against the stream, he makes no upstream progress and remains at A. Therefore, swimming with the current, his progress against ground is at the rate of 2X. 2X = .1km/(1/12) hr > X = 0.6 km/hr Master | Next Rank: 500 Posts Joined 26 Apr 2014 Posted: 199 messages Followed by: 4 members Upvotes: 16 Test Date: 7/9/2016 GMAT Score: 780 Joy Shaha wrote: Q. A swimmer swims from point A against the current for 5 minutes and then swims backward with the current for next 5 minutes and comes to the point B. If AB = 100 meters, then the speed of the current in km/hr is? a. 0.06 b. 0.2 c. 0.6 d. 1 e. None of these Strange question. Is this a GMAT question? I guess we're supposed to assume her swimming speed is equal for both intervals? If so, regor60's answer is correct. Another approach would be to assume she's a really, really slow swimmer - so slow in fact that her speed is 0. Then, all of the movement from point A to point B would be accomplished via the current. During the first 5 minutes, the current would push her back to some point x between A and B, and then during the next 5 minutes, the current would push her all the way back to point B. Since the current has moved her 100 meters in 10 minutes, the current's speed is 0.6 km/hr. _________________ 800 or bust! ### GMAT/MBA Expert GMAT Instructor Joined 12 Sep 2012 Posted: 2635 messages Followed by: 116 members Upvotes: 625 Target GMAT Score: V51 GMAT Score: 780 This looks like a question from India's CAT. Assuming her speed is constant (a major but common assumption), we'd have Against current: Her rate = r Current's rate = c Effective rate = r - c Time = 5 With current: Her rate = r Current's rate = c Effective rate = r + c Time = 5 The swimmer travels 5 * (r - c) meters AGAINST the current, then 5 * (r + c) meters WITH the current. The difference between these is the distance backward that our swimmer has traveled, so 5 * (r + c) - 5 * (r - c) = 100 10c = 100 c = 10 So the current's rate is 10 meters per minute, or 600 meters per hour, or .6 kilometers per hour. Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 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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