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

It is currently 15 Nov 2018, 00:37

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
Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • GMATbuster's Weekly GMAT Quant Quiz # 9

     November 17, 2018

     November 17, 2018

     09:00 AM PST

     11:00 AM PST

    Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

If x is a prime number, what is the number of different factors of 18x

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

Hide Tags

Intern
Intern
avatar
B
Joined: 18 Apr 2013
Posts: 34
If x is a prime number, what is the number of different factors of 18x  [#permalink]

Show Tags

New post 06 Jul 2017, 06:29
1
4
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

57% (01:39) correct 43% (01:54) wrong based on 86 sessions

HideShow timer Statistics

If x is a prime number, what is the number of different factors of 18x?
1) x^2 has 3 factors
2) x>3
Senior Manager
Senior Manager
avatar
G
Joined: 24 Apr 2016
Posts: 332
Re: If x is a prime number, what is the number of different factors of 18x  [#permalink]

Show Tags

New post 06 Jul 2017, 08:01
1
1
If x is a prime number, what is the number of different factors of 18x?

18x can be written as 2 * 3^2 * x

Case 1: If x=2, then 18x = 2^2 * 3^2 , total number of factors = 3*3 = 9
Case 2: If x=3, then 18x = 2 * 3^3 , total number of factors = 2*4 = 8
Case 3: If x= a prime number other than 2 and 3, then 18x = 2 * 3^2 * x , total number of factors = 2*3*2 = 12

So we need to find out what is the value of x?

Statement 1) x^2 has 3 factors

Square of any Prime number will have 3 factors. Eg. 2^2, 3^2, 5^2. As this statement gives no new information. This statement is not sufficient.

Statement 2) x>3

This statement clearly tells us that x is greater than 3, which means the third case is applicable here.So the total number of factors = 12. This statement is sufficient.

Answer is B
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7030
If x is a prime number, what is the number of different factors of 18x  [#permalink]

Show Tags

New post 16 Jul 2018, 18:14
roastedchips wrote:
If x is a prime number, what is the number of different factors of 18x?
1) x^2 has 3 factors
2) x>3


the answer would depend on if x is a factor of 18, that is if x is 2 or 3
If x is 2 or 3, Ans will be different ..
    a) x=2, 18*2=\(2^2*3^2....(2+1)(2+1)=3*3=9\)
    b) X=3, 18*3=2*3^3.......(1+2)(3+1)=3*4=12
If x is any other prime number, Ans will be different.
    \(18x=2*3^2*X.......(1+1)(2+1)(1+1)=2*3*2=12\)

1) \(x^2\) has 3 factors.
Just tells us that \(x^2 is square of a prime number\)
This is already known
Insufficient

2) X>3
now X is a prime number >3
Irrespective of the value of X, factors of 18x will be
18x=2*3^2*X
So factors are (1+1)(2+1)(1+1)=2*3*2=12
Sufficient

B
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

GMAT Club Bot
If x is a prime number, what is the number of different factors of 18x &nbs [#permalink] 16 Jul 2018, 18:14
Display posts from previous: Sort by

If x is a prime number, what is the number of different factors of 18x

  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®.