GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 25 May 2019, 00:35

Close

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
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.

Close

Request Expert Reply

Confirm Cancel

Set S consists of all prime numbers less than 10. If two num

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Intern
Intern
avatar
Joined: 18 Nov 2011
Posts: 34
Concentration: Strategy, Marketing
GMAT Date: 06-18-2013
GPA: 3.98
Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post Updated on: 11 Jan 2013, 13:35
2
6
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

64% (02:01) correct 36% (02:06) wrong based on 154 sessions

HideShow timer Statistics

Set S consists of all prime numbers less than 10. If two numbers are chosen from et S at random, what is the probability that the product of these numbers will be greater than the product of the numbers which were not chosen?

A. 1/3
B. 2/3
C. 1/2
D. 7/10
E. 4/5

Originally posted by hitman5532 on 11 Jan 2013, 12:45.
Last edited by Bunuel on 11 Jan 2013, 13:35, edited 1 time in total.
RENAMED THE TOPIC.
Senior Manager
Senior Manager
User avatar
Joined: 27 Jun 2012
Posts: 365
Concentration: Strategy, Finance
Schools: Haas EWMBA '17
Re: Prime integer probability  [#permalink]

Show Tags

New post 11 Jan 2013, 13:00
2
Prime integers below 10: 2, 3, 5, 7

Total outcomes: Number of ways you can choose 2 from 4 = \(4C2= 6 pairs\)
No. of ways for Event: Pairs that will have products greater than product of pairs not selected i.e. (3,5), (3,7), (5,7) \(= 3 pairs\)

Probability = number of ways/Total outcomes \(= 3/6 = 1/2\)

Hence choice(C) is correct.
_________________
Thanks,
Prashant Ponde

Tough 700+ Level RCs: Passage1 | Passage2 | Passage3 | Passage4 | Passage5 | Passage6 | Passage7
Reading Comprehension notes: Click here
VOTE GMAT Practice Tests: Vote Here
PowerScore CR Bible - Official Guide 13 Questions Set Mapped: Click here
Finance your Student loan through SoFi and get $100 referral bonus : Click here
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 55271
Re: Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post 11 Jan 2013, 13:37
2
hitman5532 wrote:
Set S consists of all prime numbers less than 10. If two numbers are chosen from et S at random, what is the probability that the product of these numbers will be greater than the product of the numbers which were not chosen?

A. 1/3
B. 2/3
C. 1/2
D. 7/10
E. 4/5


S={2, 3, 5, 7}

The simplest way would be to realize that we choose half of the numbers (basically we divide the group of 4 into two smaller groups of 2) and since a tie is not possible then the probability that the product of the numbers in either of subgroup is more than that of in another is 1/2 (the probability doesn't favor any of two subgroups).

Answer: C.

P.S. Please read carefully and follow: rules-for-posting-please-read-this-before-posting-133935.html Pay attention to the rule #3: the name of a topic (subject field) MUST be the first 40 characters (~the first two sentences) of the question.
_________________
Intern
Intern
avatar
Joined: 18 Nov 2011
Posts: 34
Concentration: Strategy, Marketing
GMAT Date: 06-18-2013
GPA: 3.98
Re: Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post 11 Jan 2013, 14:51
Bunuel wrote:
hitman5532 wrote:
Set S consists of all prime numbers less than 10. If two numbers are chosen from et S at random, what is the probability that the product of these numbers will be greater than the product of the numbers which were not chosen?

A. 1/3
B. 2/3
C. 1/2
D. 7/10
E. 4/5


S={2, 3, 5, 7}

The simplest way would be to realize that we choose half of the numbers (basically we divide the group of 4 into two smaller groups of 2) and since a tie is not possible then the probability that the product of the numbers in either of subgroup is more than that of in another is 1/2 (the probability doesn't favor any of two subgroups).

Answer: C.

P.S. Please read carefully and follow: rules-for-posting-please-read-this-before-posting-133935.html Pay attention to the rule #3: the name of a topic (subject field) MUST be the first 40 characters (~the first two sentences) of the question.


Sorry about that, failed to remember that after reading the rules a while back.

This question was nice and simple when I don't make a stupid mistake and put 9 in with the set (doh!)
Current Student
User avatar
D
Joined: 12 Aug 2015
Posts: 2617
Schools: Boston U '20 (M)
GRE 1: Q169 V154
GMAT ToolKit User
Re: Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post 07 Aug 2017, 18:13
2
Senior Manager
Senior Manager
User avatar
G
Status: Gathering chakra
Joined: 05 Feb 2018
Posts: 257
Premium Member
Re: Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post 12 Apr 2019, 05:20
Bunuel

Should we assume that the choice is without replacement if it's not directly mentioned in the prompt (something like "2 unique" or "2 different" numbers)? If we could pick the same number twice it would be 1/2 + 1/4 = 3/4, right? (since only 7*7 will be have a greater product than the remaining possibilities)
Intern
Intern
avatar
B
Joined: 18 Jul 2018
Posts: 36
Re: Set S consists of all prime numbers less than 10. If two num  [#permalink]

Show Tags

New post 14 Apr 2019, 08:31
hitman5532 wrote:
Set S consists of all prime numbers less than 10. If two numbers are chosen from et S at random, what is the probability that the product of these numbers will be greater than the product of the numbers which were not chosen?

A. 1/3
B. 2/3
C. 1/2
D. 7/10
E. 4/5


Hi, how can we know that (3,5) is the same as choosing (5,3) for example?
GMAT Club Bot
Re: Set S consists of all prime numbers less than 10. If two num   [#permalink] 14 Apr 2019, 08:31
Display posts from previous: Sort by

Set S consists of all prime numbers less than 10. If two num

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron
Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.