• NEW! FREE Beat The GMAT Quizzes
Hundreds of Questions Highly Detailed Reporting Expert Explanations
• 7 CATs FREE!
If you earn 100 Forum Points

Engage in the Beat The GMAT forums to earn
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 Problem Solving tagged by: BTGmoderatorRO This topic has 3 expert replies and 0 member replies Problem Solving If the sides of a rectangle are increased by 15%, what is the percentage increase in the area? A. 32.25% B. 40% C. 37.50% D. 36.75% E. 32% OA is C What formula do I need for this? An Expert contribution is needed please. GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Roland2rule wrote: If the sides of a rectangle are increased by 15%, what is the percentage increase in the area? A. 32.25% B. 40% C. 37.50% D. 36.75% E. 32% OA is C What formula do I need for this? An Expert contribution is needed please. Hello Roland. There is a mistake with the answer. Let's see why. Let's call the sides of the rectangle "x" and "y". Hence the area is A=x*y. Now, if each side is increased by 15%, the measure of the sides will be $$X=x+15\%\cdot x=x+0.15\cdot x=1.15\cdot x$$ $$Y=y+15\%\cdot y=y+0.15\cdot y=1.15\cdot y$$ Therefore, the area of the new rectangle is $$A_2=X\cdot Y=1.15\cdot x\cdot1.15\cdot y=1.3225\cdot xy.$$ Now, xy----------------100% 1.3225xy---------- ? Hence, the new area represents $$\frac{1.3225xy\cdot100\%}{xy}=132.25\%\ \ \text{of}\ \text{the}\ \text{first}\ \text{area}$$ This implies that the new area is 132.25%-100% = 32.25% biger than the first rectangle. So, the correct answer is A. I hope this answer may help you. I'm available if you'd like a follow-up. Regards. _________________ 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. GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15387 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 Roland2rule wrote: If the sides of a rectangle are increased by 15%, what is the percentage increase in the area? A. 32.25% B. 40% C. 37.50% D. 36.75% E. 32% Since 15% = 15/100 = 3/20, let the rectangle be a SQUARE with a side of 20. Original area = sÂ² = 20Â² = 400. After each side is increased by 15% to 23, the new area = sÂ² = 23Â² = 529. Percent increase from 400 to 529 = (Difference/Smaller) * 100 = (129/400) * 100 = 129/4 = 32.25. The correct answer is A. _________________ 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 25 Apr 2015 Posted: 2950 messages Followed by: 19 members Upvotes: 43 BTGmoderatorRO wrote: If the sides of a rectangle are increased by 15%, what is the percentage increase in the area? A. 32.25% B. 40% C. 37.50% D. 36.75% E. 32% OA is C We can let each side of the rectangle = 100, so the area is 10,000. With a 15 percent increase the new area is 115 x 115 = 13,225. Thus, the percent increase is: (13,225 - 10000)/10000 x 100% = 3225/10000 x 100 = 32.25% Answer: A _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• 5-Day Free Trial
5-day free, full-access trial TTP Quant

Available with Beat the GMAT members only code

• FREE GMAT Exam
Know how you'd score today for \$0

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

• Get 300+ Practice Questions

Available with Beat the GMAT members only code

Top First Responders*

1 Ian Stewart 44 first replies
2 Brent@GMATPrepNow 32 first replies
3 Scott@TargetTestPrep 31 first replies
4 Jay@ManhattanReview 31 first replies
5 GMATGuruNY 18 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 Scott@TargetTestPrep

Target Test Prep

138 posts
2 Max@Math Revolution

Math Revolution

85 posts
3 Ian Stewart

GMATiX Teacher

53 posts
4 Brent@GMATPrepNow

GMAT Prep Now Teacher

50 posts
5 Jay@ManhattanReview

Manhattan Review

31 posts
See More Top Beat The GMAT Experts