• 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

The ratio of local and international calls made by Amy...

This topic has 3 expert replies and 0 member replies

The ratio of local and international calls made by Amy...

Post
The ratio of local and international calls made by Amy this week is 5 to 2. If the ratio changes to 5 to 3 after Amy makes three more international calls, how many local calls did Amy make this week?

A. 3
B. 5
C. 10
D. 15
E. 21

The OA is D.

Local international ratio 5x/2x. Then local international ratio 5x/3x.

Can I say
$$\frac{5}{3}=\frac{5x}{2x+3}$$
and solve for x?

I don't have clear this PS question. I appreciate if any expert explains it to me. Thank you so much.

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post
AAPL wrote:
The ratio of local and international calls made by Amy this week is 5 to 2. If the ratio changes to 5 to 3 after Amy makes three more international calls, how many local calls did Amy make this week?

A. 3
B. 5
C. 10
D. 15
E. 21
Let L = number of local calls made this week
Let N = number of international calls made this week

The ratio of local and international calls made by Amy this week is 5 to 2
So, L/N = 5/2
Cross multiply to get: 2L = 5N

The ratio changes to 5 to 3 after Amy makes three more international calls
So, now N+3 = number of international calls made this week
And L still equals number of local calls made this week
We can write: L/(N + 3) = 5/3
Cross multiply to get: 3L = 5(N + 3)
Expand to get: 3L = 5N + 15

We know have the following system of equations
3L = 5N + 15
2L = 5N

SUBTRACT the bottom equation from the top equation to get: L = 15

Answer: D

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use my video course along with Beat The GMAT's free 60-Day Study Guide

Sign up for free Question of the Day emails
And check out all of these free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!

GMAT/MBA Expert

Legendary Member
Joined
14 Jan 2015
Posted:
2667 messages
Followed by:
122 members
Upvotes:
1153
GMAT Score:
770
Post
AAPL wrote:
The ratio of local and international calls made by Amy this week is 5 to 2. If the ratio changes to 5 to 3 after Amy makes three more international calls, how many local calls did Amy make this week?

A. 3
B. 5
C. 10
D. 15
E. 21

The OA is D.

Local international ratio 5x/2x. Then local international ratio 5x/3x.

Can I say
$$\frac{5}{3}=\frac{5x}{2x+3}$$
and solve for x?

I don't have clear this PS question. I appreciate if any expert explains it to me. Thank you so much.
You could also back-solve and use a little logic. First, we know that local calls must be a multiple of 5, so only B, C, and D are options.
Next, we can see quickly that B doesn't make sense - if there had been exactly 5 local calls and 2 international calls, if 3 more international calls had been made, the ratio would have been 5:5, not 5:3. B is out.

Now we just have to test one of the two remaining answer choices. If it works, it's our answer. If it doesn't, the other is our answer.
If there had been 10 local calls, then there'd have been 4 international calls. (10:4 = 5:2.) If there'd been 3 more international calls, the ratio would have been 10:7. We want 5:3. So C is out.

We're left with D

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course

  • +1 Upvote Post
  • Quote
  • Flag
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!
Post
AAPL wrote:
The ratio of local and international calls made by Amy this week is 5 to 2. If the ratio changes to 5 to 3 after Amy makes three more international calls, how many local calls did Amy make this week?

A. 3
B. 5
C. 10
D. 15
E. 21
The ratio of local to international calls is 5x : 2x. Since after three more international calls are made, resulting in a new ratio of 5 to 3, we can create the equation:

5x/(2x + 3) = 5/3

15x = 5(2x + 3)

3x = 2x + 3

x = 3

So Amy made 5(3) = 15 local calls this week.

Answer: D

_________________

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

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas 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

Top First Responders*

1 Ian Stewart 53 first replies
2 Brent@GMATPrepNow 36 first replies
3 Jay@ManhattanReview 29 first replies
4 GMATGuruNY 25 first replies
5 ceilidh.erickson 15 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

199 posts
2 image description Max@Math Revolution

Math Revolution

90 posts
3 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

76 posts
4 image description Ian Stewart

GMATiX Teacher

62 posts
5 image description GMATGuruNY

The Princeton Review Teacher

44 posts
See More Top Beat The GMAT Experts