Last visit was: 15 Aug 2024, 12:04 It is currently 15 Aug 2024, 12:04
Toolkit
GMAT Club Daily Prep
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

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.

# A dog breeder currently has 9 breeding dogs. 6 of the dogs have exactl

SORT BY:
Tags:
Show Tags
Hide Tags
Manager
Joined: 05 Nov 2012
Status:GMAT Coach
Posts: 157
Own Kudos [?]: 295 [0]
Given Kudos: 65
Location: Peru
GPA: 3.98
Manager
Joined: 05 Nov 2012
Status:GMAT Coach
Posts: 157
Own Kudos [?]: 295 [0]
Given Kudos: 65
Location: Peru
GPA: 3.98
GMAT Club Legend
Joined: 19 Dec 2014
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Posts: 21835
Own Kudos [?]: 11831 [0]
Given Kudos: 450
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Manager
Joined: 22 Sep 2018
Posts: 191
Own Kudos [?]: 182 [0]
Given Kudos: 78
Re: A dog breeder currently has 9 breeding dogs. 6 of the dogs have exactl [#permalink]
sm021984 wrote:
A dog breeder currently has 9 breeding dogs. 6 of the dogs have exactly 1 littermate, and 3 of the dogs have exactly 2 littermates. If 2 dogs are selected at random, what is the probability that both selected dogs are NOT littermates?

A. 1/6
B. 2/9
C. 5/6
D. 7/9
E. 8/9

My thought process if it helps anyone:

out of 9 dogs we can pair them in 36 ways or $$9C2$$

Probability we can pick a sibling + probability we don't pick a sibling = 1

To pick a sibling we have 3 pairs and one triple

So:

$$2C2 + 2C2 + 2C2 + 3C2 = 6$$

there is $$\frac{1}{6}$$ chance to select a sibling

Hence $$\frac{5}{6}$$ we do not select a sibling.
Non-Human User
Joined: 09 Sep 2013
Posts: 34440
Own Kudos [?]: 865 [0]
Given Kudos: 0
Re: A dog breeder currently has 9 breeding dogs. 6 of the dogs have exactl [#permalink]
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 dog breeder currently has 9 breeding dogs. 6 of the dogs have exactl [#permalink]
1   2
Moderator:
Math Expert
94967 posts