Last visit was: 18 Jul 2024, 21:52 It is currently 18 Jul 2024, 21:52
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
SORT BY:
Date
Tags:
Show Tags
Hide Tags
User avatar
Senior Manager
Senior Manager
Joined: 25 Jun 2011
Status:Finally Done. Admitted in Kellogg for 2015 intake
Posts: 395
Own Kudos [?]: 17032 [47]
Given Kudos: 217
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE:Information Technology (Consulting)
Send PM
Most Helpful Reply
Math Expert
Joined: 02 Sep 2009
Posts: 94407
Own Kudos [?]: 642129 [12]
Given Kudos: 85997
Send PM
General Discussion
User avatar
Manager
Manager
Joined: 22 Apr 2011
Posts: 103
Own Kudos [?]: 609 [1]
Given Kudos: 18
Concentration: Accounting
Schools:Mccombs business school, Mays business school, Rotman Business School,
 Q47  V28 GMAT 2: 570  Q40  V29
GPA: 3.44
Send PM
User avatar
Manager
Manager
Joined: 30 Jun 2011
Affiliations: Project Management Professional (PMP)
Posts: 98
Own Kudos [?]: 155 [0]
Given Kudos: 12
Location: New Delhi, India
Concentration: Marketing
Send PM
Re: coprime [#permalink]
alchemist009 wrote:
An infinite sequence of positive integers is called a “"coprime
sequence" ”if no term in the sequence shares a common divisor
(except 1) with any other term in the sequence. If S is an inf…inite
sequence of distinct positive integers, is S a coprime sequence?
(1) An in…finite number of integers in S are prime.
(2) Each term in S has exactly two factors.

does the statement 1 mean that all numbers in sequence S are prime???

IMO answer is "B"
we have to determine if all the integers in series are prime or not

stm 1: it says number of integers is prime so the series can contain prime numbers or not hence : NOT SUFFICIENT

Stm 2: Each number is a prime number : Hence SUFFICIENT
User avatar
Manager
Manager
Joined: 25 Oct 2013
Posts: 114
Own Kudos [?]: 166 [2]
Given Kudos: 55
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
2
Kudos
Nice, nice nice. Fell into trap and chose wrong answer. Statement 1 seems like each number in s is prime but it is not! Statement 2 makes it look like the numbers are not prime but indeed they are!
avatar
Intern
Intern
Joined: 28 Jul 2013
Posts: 45
Own Kudos [?]: 100 [0]
Given Kudos: 37
Location: India
Concentration: Marketing, Strategy
GPA: 3.62
WE:Engineering (Manufacturing)
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
Bunuel: if two terms are 2 in the sequence S....(2,2,3,4,5..............) here the two terms have 2 as a common divisor. The question says that a coprime sequence will not have any other factor common to any other number except 1.
Tutor
Joined: 16 Oct 2010
Posts: 15124
Own Kudos [?]: 66721 [1]
Given Kudos: 436
Location: Pune, India
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
1
Kudos
Expert Reply
sayansarkar wrote:
Bunuel: if two terms are 2 in the sequence S....(2,2,3,4,5..............) here the two terms have 2 as a common divisor. The question says that a coprime sequence will not have any other factor common to any other number except 1.


You are given that S has distinct integers. So two terms cannot be 2 each.
avatar
Intern
Intern
Joined: 28 Jul 2013
Posts: 45
Own Kudos [?]: 100 [0]
Given Kudos: 37
Location: India
Concentration: Marketing, Strategy
GPA: 3.62
WE:Engineering (Manufacturing)
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
Thanks Karishma....You have discovered my other problem....I tend to read super fast and miss things in the process....my biggest weakness...
Tutor
Joined: 16 Oct 2010
Posts: 15124
Own Kudos [?]: 66721 [0]
Given Kudos: 436
Location: Pune, India
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
Expert Reply
sayansarkar wrote:
Thanks Karishma....You have discovered my other problem....I tend to read super fast and miss things in the process....my biggest weakness...


Reading super fast is great for RC. For all others, it is not advisable. You have enough time so slow down a bit.
Senior Manager
Senior Manager
Joined: 11 May 2014
Status:I don't stop when I'm Tired,I stop when I'm done
Posts: 473
Own Kudos [?]: 39410 [0]
Given Kudos: 220
Location: Bangladesh
Concentration: Finance, Leadership
GPA: 2.81
WE:Business Development (Real Estate)
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
Bunuel wrote:
An infi…nite sequence of positive integers is called a “coprime sequence ”if no term in the sequence shares a common divisor (except 1) with any other term in the sequence. If S is an in…finite sequence of distinct positive integers, is S a coprime sequence?

Notice that S is an in…finite sequence of distinct positive integers.

(1) An infinite number of integers in S are prime --> obviously these primes will be coprime to each other. But we don't know whether the sequence contains some numbers other than primes, and if it does then the sequence won't be coprime (for example the sequence can contain 4 and 6 in addition to these primes). Not Sufficient.

(2) Each term in S has exactly two factors --> each term in S is a prime, so S contains only distinct primes, which will be coprime. Sufficient.

Answer: B.


Great analysis.

Can you just provide similar tricky(referred to Statement 1 type trap) question to practice?

Thanks
Senior Manager
Senior Manager
Joined: 15 Jan 2017
Posts: 257
Own Kudos [?]: 87 [0]
Given Kudos: 932
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
A) An infinite number of integers in S are prime.
^ would mean; what about the other integers? there maybe infinite PRIME integers in S but what about non prime?So NS
B)Each term in S has exactly two factors.
Only a prime has ITSELF and one as their factors.

B is Sufficient
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 34014
Own Kudos [?]: 852 [0]
Given Kudos: 0
Send PM
Re: An infinite sequence of positive integers is called a coprime sequence [#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.
GMAT Club Bot
Re: An infinite sequence of positive integers is called a coprime sequence [#permalink]
Moderator:
Math Expert
94407 posts