• NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    NEW! FREE Beat The GMAT Quizzes
    Hundreds of Questions Highly Detailed Reporting Expert Explanations TAKE A FREE GMAT QUIZ
  • 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 Prep
    VERITAS PRACTICE GMAT EXAMS
    Earn 10 Points Per Post
    Earn 10 Points Per Thanks
    Earn 10 Points Per Upvote
    REDEEM NOW

Problem Solving

This topic has 3 expert replies and 0 member replies

Problem Solving

Post
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.

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
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.

  • +1 Upvote Post
  • Quote
  • Flag
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

Post
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 = s² = 20² = 400.
After each side is increased by 15% to 23, the new area = s² = 23² = 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

  • +1 Upvote Post
  • Quote
  • Flag
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.
Post
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

  • +1 Upvote Post
  • Quote
  • Flag
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer

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 image description Scott@TargetTestPrep

Target Test Prep

138 posts
2 image description Max@Math Revolution

Math Revolution

85 posts
3 image description Ian Stewart

GMATiX Teacher

53 posts
4 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

50 posts
5 image description Jay@ManhattanReview

Manhattan Review

31 posts
See More Top Beat The GMAT Experts