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

It is currently 20 Oct 2018, 12:22

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

Is the positive integer x a prime number? (1) x is even (2) 2< x < 19

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50007
Is the positive integer x a prime number? (1) x is even (2) 2< x < 19  [#permalink]

Show Tags

New post 10 Jun 2018, 04:54
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

83% (00:29) correct 17% (00:19) wrong based on 30 sessions

HideShow timer Statistics

Manager
Manager
avatar
B
Joined: 10 Jun 2018
Posts: 54
Location: Australia
Concentration: Technology, General Management
GPA: 2.88
WE: Science (Pharmaceuticals and Biotech)
Is the positive integer x a prime number? (1) x is even (2) 2< x < 19  [#permalink]

Show Tags

New post Updated on: 10 Jun 2018, 18:03
We can substitute numbers to quickly figure this answer out.

With statement (1), 2 is a prime number, 4 is not. So not sufficient.
With statement (2), 3 is a prime number, 4 is not. So not sufficient.

Combined, with have something interesting. 2 is the only prime even number, and since we cannot include it, then all other even numbers we can think of will not be prime numbers. Regardless of whether x = 4, 6, 8, 10, 12, 14, 16, or 18, they'd all not be prime numbers. Hence together, statements (1) and (2) are sufficient. I.e. answer is C.

Another way to approach this question is to think back to the rules of prime numbers. Statement (1) cannot be sufficient because it includes both 2 and other even numbers, and we know 2 is a prime number while the others are not. Statement (2) include odd numbers, including a bunch that are definitely prime numbers, but also even numbers that are not. Combined, statement (2) actually only serves to rule out the number 2 as a possible even number for x. You don't and shouldn't even care about the fact that x has to be less than 19. The only time it'd matter is if x has to be < 4 or something, but that's not the case here, and I doubt would ever be the case in these sort of questions.
_________________

Not a professional entity or a quant/verbal expert or anything. So take my answers with a grain of salt.


Originally posted by Azedenkae on 10 Jun 2018, 07:19.
Last edited by Azedenkae on 10 Jun 2018, 18:03, edited 1 time in total.
Manager
Manager
avatar
B
Joined: 16 May 2017
Posts: 52
Location: India
Re: Is the positive integer x a prime number? (1) x is even (2) 2< x < 19  [#permalink]

Show Tags

New post 10 Jun 2018, 07:51
Stmt :1 says X is even,X can be 2 or 4 , may be Prime (2) or not a prime (4) Not sufficient

Stmt:2 2< x < 19 ,greater than 2 , lot of possible integers from 3 to 18 which can be prime no(3,5,7,11,13,17) and also non prime no(4,6,8 and so on) Not sufficient.

Combining 1& 2

Stmt 1 says X is even and stmt say x greater than 2 and less than 19,hence the x is non prime number ,only even prime no is 2.
Hence C,
Intern
Intern
avatar
B
Joined: 29 Jan 2018
Posts: 3
GMAT 1: 770 Q50 V42
Re: Is the positive integer x a prime number? (1) x is even (2) 2< x < 19  [#permalink]

Show Tags

New post 10 Jun 2018, 11:48
We are given that x is a positive integer.

We have to analyze if x is a prime number or not.

(1): "x is even" - All even numbers with the exception of 2 are non-prime. We cannot be sure if x is prime or not. INSUFFICIENT.

(2): "2<x<19" - x can be any integer 2 and 19. There are both primes and non-primes in that range. INSUFFICIENT.

(1)+(2): " x is an even number greater than 2 and less than 19" - All possible values of x will be non-prime since 2 is the only prime even number and that is excluded from the range. Therefore, SUFFICIENT.

Answer: C
Director
Director
User avatar
G
Joined: 31 Oct 2013
Posts: 651
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
Is the positive integer x a prime number? (1) x is even (2) 2< x < 19  [#permalink]

Show Tags

New post 10 Jun 2018, 19:44
Bunuel wrote:
Is the positive integer x a prime number?

(1) x is even
(2) 2< x < 19



Note:

1. x is a positive integer.
2. Need to fin out whether x is prime or not

Statement 1:

x is even. There are hundreds of even numbers . Among them only 2 is the prime. But no relevant information is given.

Not stuff.

Statement 2:

Range of numbers is given: 2<x<19

in this range prime and non prime numbers both are here. Suppose, 3 ,5 , 7 10 all fall under this range . but 10 is not prime.

Not stuff.

Both Statements Together:

1. it states that x is even
2. 2<x<19

There are several even numbers in this range but they are not prime. So, x is not a prime. we got the answer.

Thus, both statements together are sufficient. Thew correct answer is C.

Note: only 2 is the even prime on earth.
GMAT Club Bot
Is the positive integer x a prime number? (1) x is even (2) 2< x < 19 &nbs [#permalink] 10 Jun 2018, 19:44
Display posts from previous: Sort by

Is the positive integer x a prime number? (1) x is even (2) 2< x < 19

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


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®.