May 25 07:00 AM PDT  09:00 AM PDT Attend this webinar and master GMAT SC in 10 days by learning how meaning and logic can help you tackle 700+ level SC questions with ease. May 27 01:00 AM PDT  11:59 PM PDT All GMAT Club Tests are free and open on May 27th for Memorial Day! May 27 10:00 PM PDT  11:00 PM PDT Special savings are here for Magoosh GMAT Prep! Even better  save 20% on the plan of your choice, now through midnight on Tuesday, 5/27 May 30 10:00 PM PDT  11:00 PM PDT Application deadlines are just around the corner, so now’s the time to start studying for the GMAT! Start today and save 25% on your GMAT prep. Valid until May 30th. Jun 01 07:00 AM PDT  09:00 AM PDT Learn reading strategies that can help even nonvoracious reader to master GMAT RC
Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 18 Nov 2011
Posts: 34
Concentration: Strategy, Marketing
GMAT Date: 06182013
GPA: 3.98

Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
Updated on: 11 Jan 2013, 13:35
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
Official Answer and Stats are available only to registered users. Register/ Login.
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
Joined: 27 Jun 2012
Posts: 365
Concentration: Strategy, Finance

Re: Prime integer probability
[#permalink]
Show Tags
11 Jan 2013, 13:00
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  Passage7Reading Comprehension notes: Click hereVOTE GMAT Practice Tests: Vote HerePowerScore CR Bible  Official Guide 13 Questions Set Mapped: Click hereFinance your Student loan through SoFi and get $100 referral bonus : Click here



Math Expert
Joined: 02 Sep 2009
Posts: 55271

Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
11 Jan 2013, 13:37
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: rulesforpostingpleasereadthisbeforeposting133935.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
Joined: 18 Nov 2011
Posts: 34
Concentration: Strategy, Marketing
GMAT Date: 06182013
GPA: 3.98

Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
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: rulesforpostingpleasereadthisbeforeposting133935.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
Joined: 12 Aug 2015
Posts: 2617

Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
07 Aug 2017, 18:13
Primes in action > 2,3,5,7 Cases > 2,3 => (NO) 2,5 => (NO) 2,7 => (NO) 3,5 => (YES) 3,7 => (YES) 5,7 => (YES) Total cases > 6 Favourable cases > 3 P(E) => 3/6 => 1/2 Hence C.
_________________



Senior Manager
Status: Gathering chakra
Joined: 05 Feb 2018
Posts: 257

Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
12 Apr 2019, 05:20
BunuelShould 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
Joined: 18 Jul 2018
Posts: 36

Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
Show Tags
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?




Re: Set S consists of all prime numbers less than 10. If two num
[#permalink]
14 Apr 2019, 08:31






