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

 It is currently 20 Jul 2018, 11:43

### 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

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

# What is the greatest common factor of the positive integers x and y? 1

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

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 47157
What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

11 Apr 2016, 04:04
1
4
00:00

Difficulty:

15% (low)

Question Stats:

74% (00:40) correct 26% (00:45) wrong based on 139 sessions

### HideShow timer Statistics

What is the greatest common factor of the positive integers x and y?

(1) x = y^20
(2) $$y=\sqrt[5]{243}$$

_________________
SC Moderator
Joined: 13 Apr 2015
Posts: 1712
Location: India
Concentration: Strategy, General Management
GMAT 1: 200 Q1 V1
GPA: 4
WE: Analyst (Retail)
What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

11 Apr 2016, 20:44
St1: x = y^20
If y = 3 and x = 3^20 then GCD(3^20, 3) = 3; LCM(3^20, 3) = 3^20
If y = 2 and x = 2^20 then GCD(2^20, 2) = 2; LCM(2^20, 2) = 2^20
Thus GCD(x, y) = GCD(y^20, y) = y
Not Sufficient.

St2: y = 3; Clearly insufficient as we do not know the value of x. If x = 2 then GCD = 1 but if x = 3^2 then GCD(x, y) = 3

Combining St1 and St2, we have that GCD(x, y) = y = 3

Manager
Joined: 15 Jul 2015
Posts: 52
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

11 Apr 2016, 23:40
1
GCD(y, y^20) = y
St. 1 insufficient

y = (243)^(1/5) = 3
But doesn't give any info of x
St. 2 insufficient

Both statements when combined tell us GCD = 3

hence C.

Posted from my mobile device
_________________

I am not an expert, so please CORRECT me if I am wrong

Intern
Joined: 05 Feb 2016
Posts: 9
GMAT 1: 510 Q39 V21
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

13 Apr 2016, 02:31
GCD (x,y) = ?

1) x = y^20

y.y.y.y.y.y.y.y.y.y.y.y.y.y.y.y.y.y.y.y
y
--------------------
GCD (x,y)= y
Insufficient

2) y = 243^1/5 x = ?
Insufficient

1)2) GCD (x,y)= y
y = 243^1/5
y = 3
GCD (x,y) = 3
SUFFICIENT
_________________

What we do in life, echoes in eternity...

BSchool Forum Moderator
Joined: 12 Aug 2015
Posts: 2648
GRE 1: Q169 V154
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

15 Apr 2016, 05:25
Current Student
Status: It`s Just a pirates life !
Joined: 21 Mar 2014
Posts: 235
Location: India
Concentration: Strategy, Operations
GMAT 1: 690 Q48 V36
GPA: 4
WE: Consulting (Manufacturing)
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

18 Apr 2016, 04:06
Bunuel wrote:
What is the greatest common factor of the positive integers x and y?

(1) x = y^20
(2) $$y=\sqrt[5]{243}$$

C...good question to build GCD concepts
_________________

Aiming for a 3 digit number with 7 as hundredths Digit

Intern
Joined: 08 Apr 2016
Posts: 3
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

18 Apr 2016, 07:22
I do not think any calculation is needed here. We can save a lot of time by avoiding un-necessary calculations

1) x = y^ 20 = y*y*.......*y
we do not know the value of x or y and hence statement 1 is insufficient

2) y = (243) ^ 1/5 = some definite value (someone above has mentioned that (243)^1/3 = 3 but I do not think we need to do this calculation)
So, statement 2 gives us the value of y but not of x and hence it is insufficient

Now, combine 1 & 2,
putting the definite value of y in 1st equation, we can find a definite value of x.

At the end we can calculate a GCD of 2 definite values but there is no need to do actual calculations.
Both 1 and 2 together are sufficient and hence C is the answer

This is a data sufficiency question and not a problem solving one. Try to save your time by avoiding un-necessary calculations
Non-Human User
Joined: 09 Sep 2013
Posts: 7312
Re: What is the greatest common factor of the positive integers x and y? 1  [#permalink]

### Show Tags

12 Sep 2017, 07:24
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.
_________________
Re: What is the greatest common factor of the positive integers x and y? 1 &nbs [#permalink] 12 Sep 2017, 07:24
Display posts from previous: Sort by

# What is the greatest common factor of the positive integers x and y? 1

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

# Events & Promotions

 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®.