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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 ## Arithmetic tagged by: BTGmoderatorRO ##### This topic has 1 expert reply and 0 member replies ## Arithmetic Which of the following is the closest approximation to $$\frac{\left[[\sqrt{73}\cdot\sqrt{239}\ \right]}{\left[\sqrt{7.2}+\sqrt{15.7}\right]}$$ A. 10 B. 15 C. 20 D. 25 E. 30 What's the best way to determine the correct answer here? ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Quote: Which of the following is the closest approximation to $$\frac{\left[[\sqrt{73}\cdot\sqrt{239}\ \right]}{\left[\sqrt{7.2}+\sqrt{15.7}\right]}$$ A. 10 B. 15 C. 20 D. 25 E. 30 What's the best way to determine the correct answer here? Hi Roland2rule, Let's take a look at your question. $$\frac{\sqrt{73}\sqrt{239}}{\sqrt{7.2}+\sqrt{15.7}}$$ We are asked to approximate its value, so let's first approximate all the numbers used in the square roots with the closest possible number that is a perfect square. Using approximation we can rewrite the given expression as, $$\approx\frac{\sqrt{81}\sqrt{225}}{\sqrt{9}+\sqrt{16}}$$ Now it seems pretty simple to evaluate it, since all the numbers are now perfect squares. $$\approx\frac{9\times15}{3+4}$$ $$\approx\frac{9\times15}{7}$$ To make the calculation more simple, let's write 14 instead of 15 in the numerator because it is the multiple of 7 closest to 15. So the expression will look like: $$\approx\frac{9\times14}{7}$$ $$\approx9\times2\approx18$$ The closest possible value to 18 in the given options is 20. Therefore, Option C is correct. Hope it helps. I am available if you'd like any follow up. _________________ GMAT Prep From The Economist We offer 70+ point score improvement money back guarantee. Our average student improves 98 points. Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now. • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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