Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

16 Aug 2003, 05:56

3

This post received KUDOS

28

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

45% (medium)

Question Stats:

67% (01:41) correct
33% (02:11) wrong based on 498 sessions

HideShow timer Statistics

A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store?

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

16 Aug 2003, 06:06

e?
we have c cats and d dogs... d=c+13... so our ratio is c/d=c/(c+13)... if we plug every answer (not very elegant, i admit it), we see that the only way to get an integer for c is 4/5

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

18 Aug 2003, 02:17

1

This post was BOOKMARKED

yes E. 4:5 is the correct answer.
the difference between the number of cats and dogs must be divisible by difference between the numbers that represent both animals in ratio. Since 13 is a prime number , it is only divisible by 1 and 13 .Therefore, the correct choice is the one where the difference between the numbers is 1.

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

30 Jul 2014, 20:53

araspai wrote:

1. A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store? a. 1:3 b. 1:4 c. 1:5 d. 2:5 e. 4:5

I got this same exercise but with diff options: a)4:1 b)3:1 c)4:3 d)5:2 e)5:3

The answer is C. Bunnuel, could you please help and explain it to us? Thank you!

1. A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store? a. 1:3 b. 1:4 c. 1:5 d. 2:5 e. 4:5

I got this same exercise but with diff options: a)4:1 b)3:1 c)4:3 d)5:2 e)5:3

The answer is C. Bunnuel, could you please help and explain it to us? Thank you!

A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store?

A. 1:3 B. 1:4 C. 1:5 D. 2:5 E. 4:5

Say the ratio of cats to dogs is a/b. Then the number of cats would be ax and the number of dogs bx, for some positive integer x.

We are told that ax - bx = 13 --> x(a - b) = 13. Since 13 is a prime number it could be broken into the product of two positive multiples only in one way: x(a - b) = 1*13.

The above implies that either x = 1 and a - b = 13 or x = 13 and a - b = 1.

Therefore the correct answer should have the difference between numerator and denominator equal to 1 or 13.

For the original question only option which fits is E, 4:5. Cats = 13*4 = 52 and dogs = 13*5 = 65.

Answer: E.

For your question the answer would be C, 4:3, for the same reason. _________________

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

08 Aug 2014, 22:19

1

This post was BOOKMARKED

Bunuel wrote:

Reni wrote:

araspai wrote:

1. A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store? a. 1:3 b. 1:4 c. 1:5 d. 2:5 e. 4:5

I got this same exercise but with diff options: a)4:1 b)3:1 c)4:3 d)5:2 e)5:3

The answer is C. Bunnuel, could you please help and explain it to us? Thank you!

A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store?

A. 1:3 B. 1:4 C. 1:5 D. 2:5 E. 4:5

Say the ratio of cats to dogs is a/b. Then the number of cats would be ax and the number of dogs bx, for some positive integer x.

We are told that ax - bx = 13 --> x(a - b) = 13. Since 13 is a prime number it could be broken into the product of two positive multiples only in one way: x(a - b) = 1*13.

The above implies that either x = 1 and a - b = 13 or x = 13 and a - b = 1.

Therefore the correct answer should have the difference between numerator and denominator equal to 1 or 13.

For the original question only option which fits is E, 4:5. Cats = 13*4 = 52 and dogs = 13*5 = 65.

Answer: E.

For your question the answer would be C, 4:3, for the same reason.

I understood till this point : The above implies that either x = 1 and a - b = 13 or x = 13 and a - b = 1. But how can you deduce this from above : Therefore the correct answer should have the difference between numerator and denominator equal to 1 or 13. Please explain.

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

15 Aug 2015, 03:20

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

28 Oct 2015, 12:59

3

This post received KUDOS

1

This post was BOOKMARKED

The logic I used to answer this question is this: I thought about the difference between both C - D = 13 Which means that (if you didn't look at the answer choices) you could technically pick any ratio where the differences were 13. For instance: 7:20 , 6:19 , 1:14 , etc etc, All of these ratios are correct, but the problem here is that we do not have any answer choices that will match this, which is why it is safe to multiply each answer choice by 13 to see which ones will give you a difference of 13 when you subtract them by one another.

D) 4:5 ---> (13)* 4:5 *(13) ===> 52:65 , which when you subtract these it gives you 65-52 = 13.

This is a much easier way to tackle this problem just by looking at the problem statement and realizing that your answer is not amongst one of them.

That's a clever way to interpret this question and it showcases how paying attention to the answer choices (and using them to your advantage) can lead to quicker solutions to a given question (than just doing long-winded calculations).

A pet store holds cats and dogs. If the difference between the number of cats and the number of dogs is 13. What could be the ratio of Cats to dogs in the pet store?

A. 1:3 B. 1:4 C. 1:5 D. 2:5 E. 4:5

This question tests your understanding of the ratio scale vs actual values. If you recognise it, it takes you a few secs to get to your answer. This concept has been discussed in detail here: http://www.veritasprep.com/blog/2011/03 ... of-ratios/

We all are aware that to convert ratio scale values to actual values, we multiply the ratio by the multiplier. We have also often used the sum of values concept for the "total" of actual values. This question tests the same concept with the difference between values. If the actual difference between values is 13, what could be the difference in values on the ratio scale? To get 13, the multiplier could have been 1 or 13. In case it was 1, then the difference between the values on ratio scale would be 13. If instead, the multiplier is 13, the difference between the values on the ratio scale would be 1. Only option (E) satisfies this condition (difference between values on ratio scale is 1)
_________________

Re: A pet store holds cats and dogs. If the difference between [#permalink]

Show Tags

17 Mar 2017, 09:45

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Version 8.1 of the WordPress for Android app is now available, with some great enhancements to publishing: background media uploading. Adding images to a post or page? Now...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...