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

 It is currently 22 Oct 2019, 07:43 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  If x is the greatest common divisor of 90 and 18, and y is the least

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

Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 58431
If x is the greatest common divisor of 90 and 18, and y is the least  [#permalink]

Show Tags 00:00

Difficulty:   25% (medium)

Question Stats: 77% (01:32) correct 23% (01:53) wrong based on 87 sessions

HideShow timer Statistics

If x is the greatest common divisor of 90 and 18, and y is the least common multiple of 51 and 34, then x + y =

A. 111
B. 120
C. 213
D. 222
E. 231

_________________
Intern  B
Joined: 17 Dec 2016
Posts: 19
Location: Viet Nam
Re: If x is the greatest common divisor of 90 and 18, and y is the least  [#permalink]

Show Tags

Finding x - GCD (90 ,18)
90 = 2 x $$3^2$$ x 5
18 = 2 x $$3^2$$

--> x = 2 x $$3^2$$ = 18

Finding y - LCM (51,34)
51 = 3 x 17
34 = 2 x 17

--> y = 2 x 3 x 17 = 102

--> x + y = 102 + 18 = 120

--> Option B is the answer

Let me know your thought. Thank you
Senior PS Moderator D
Status: It always seems impossible until it's done.
Joined: 16 Sep 2016
Posts: 737
GMAT 1: 740 Q50 V40 GMAT 2: 770 Q51 V42 Re: If x is the greatest common divisor of 90 and 18, and y is the least  [#permalink]

Show Tags

Bunuel wrote:
If x is the greatest common divisor of 90 and 18, and y is the least common multiple of 51 and 34, then x + y =

A. 111
B. 120
C. 213
D. 222
E. 231

To find the GCD and LCM of two numbers always denote the numbers in the prime factorization form -

First pair:
$$18 = 2^1*3^2$$
$$90 = 2^1*3^2*5^1$$

To find GCD of these two numbers - find the common factors ( along with powers) : So GCD would be : $$2^1*3^2 = 18$$

Second pair:

$$51 = 3^1*17^1$$
$$34 = 2^1*17^1$$

So GCD is $$17^1 = 17$$ and the LCM is (First number * Second number)/GCD = $$\frac{(3^1*17^1*2^1*17^1)}{17^1} =$$$$3*2*17$$

Hence the question is asking $$18 + 6*17 = 18 + 102 = 120$$

Hence Option (B) is our choice.

Regards,
_________________
Regards,

“Do. Or do not. There is no try.” - Yoda (The Empire Strikes Back)
Director  V
Joined: 06 Jan 2015
Posts: 689
Location: India
Concentration: Operations, Finance
GPA: 3.35
WE: Information Technology (Computer Software)
Re: If x is the greatest common divisor of 90 and 18, and y is the least  [#permalink]

Show Tags

Bunuel wrote:
If x is the greatest common divisor of 90 and 18, and y is the least common multiple of 51 and 34, then x + y =

A. 111
B. 120
C. 213
D. 222
E. 231

If x is the greatest common divisor of 90 and 18 then x=18

And y is the least common multiple of 51 and 34 then y=102

x+y = 18+102 = 120

Hence B
_________________
आत्मनॊ मोक्षार्थम् जगद्धिताय च

Resource: GMATPrep RCs With Solution
Target Test Prep Representative D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8125
Location: United States (CA)
Re: If x is the greatest common divisor of 90 and 18, and y is the least  [#permalink]

Show Tags

Bunuel wrote:
If x is the greatest common divisor of 90 and 18, and y is the least common multiple of 51 and 34, then x + y =

A. 111
B. 120
C. 213
D. 222
E. 231

Factoring 18 and 90, we get: 18 = 9 x 2 = 2 x 3^2 and 90 = 9 x 10 = 2 x 3^2 x 5

The GCF of 18 and 90 is 2 x 3^2 = 18. This is the value of x.

Factoring 51 and 34, we get: 51 = 3 x 17 and 34 = 2 x 17

The LCM of 51 and 34 is 17 x 2 x 3 = 102. This is the value of y.

Thus, the sum of x and y is 18 + 102 = 120.

_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button. Re: If x is the greatest common divisor of 90 and 18, and y is the least   [#permalink] 18 Oct 2018, 18:29
Display posts from previous: Sort by

If x is the greatest common divisor of 90 and 18, and y is the least

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

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne  