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

It is currently 22 Aug 2018, 00:54

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

If k is the smallest positive integer such that 2,940k

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

Hide Tags

Intern
Intern
avatar
Joined: 16 Feb 2013
Posts: 6
If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 04 May 2013, 10:17
4
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

71% (01:35) correct 29% (01:40) wrong based on 166 sessions

HideShow timer Statistics

If k is the smallest positive integer such that 2,940k is the square of an integer, then k must be

A. 3
B. 5
C. 6
D. 15
E. 21
Intern
Intern
avatar
Joined: 23 Apr 2013
Posts: 21
Re: If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 04 May 2013, 10:52
1
streamingline wrote:
If k is the smallest positive integer such that 2,940k is the square of an integer, then k must be

A)3
B)5
C)6
D)15
E)21


Spoiler: :: OA
15


\(2940 = 2^2 * 3 * 5 * 7^2\)

So the smallest positive integer to be multiplied to make it a perfect square is 3 * 5 = 15

Correct Option is D :)
Intern
Intern
avatar
Joined: 16 Feb 2013
Posts: 6
Re: If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 04 May 2013, 19:35
Thanks, didn't realise K was multiplied by 2940
Manager
Manager
User avatar
S
Joined: 03 Aug 2015
Posts: 56
Concentration: Strategy, Technology
Schools: ISB '18, SPJ GMBA '17
GMAT 1: 680 Q48 V35
Reviews Badge
Re: If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 11 Jan 2016, 08:23
streamingline wrote:
If k is the smallest positive integer such that 2,940k is the square of an integer, then k must be

A. 3
B. 5
C. 6
D. 15
E. 21



Hi,

Pls clarify whether K is a unit digit of the given No. or it is in multiplication?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 48119
Re: If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 11 Jan 2016, 08:24
ArunpriyanJ wrote:
streamingline wrote:
If k is the smallest positive integer such that 2,940k is the square of an integer, then k must be

A. 3
B. 5
C. 6
D. 15
E. 21



Hi,

Pls clarify whether K is a unit digit of the given No. or it is in multiplication?


It's a multiplication sign.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 1916
Premium Member CAT Tests
If k is the smallest positive integer such that 2,940k  [#permalink]

Show Tags

New post 06 Jul 2018, 10:04
1
streamingline wrote:
If k is the smallest positive integer such that 2,940k is the square of an integer, then k must be

A. 3
B. 5
C. 6
D. 15
E. 21

• Perfect square rule: A perfect square always has an even number of powers of prime factors.
That rule is often easier to remember this way:
all prime factors must come in pairs. Couplets.

There are no single "copies" of a prime factor in a perfect square.
If there is only one "copy" of a prime factor, or an odd number of copies, then the integer is not a perfect square.

• \(2,940 * k\) is a perfect square

Prime factorize: \(2,940= 2 * 2 *3*5*7*7\)
This situation will not make a perfect square.
The 3s and the 5s are not in pairs. We need one more copy of each.
(We have \(3^1\) and \(5^1\), but exponents on prime factors must be even.)

\(k\) is the number that provides the extra \(3\) and the extra \(5\)
\(k = 3*5 = 15\)

ANSWER D

\(2,940 * (3*5) = 44,100\), which is \(210^2\)
_________________

In the depths of winter, I finally learned
that within me there lay an invincible summer.

-- Albert Camus, "Return to Tipasa"

If k is the smallest positive integer such that 2,940k &nbs [#permalink] 06 Jul 2018, 10:04
Display posts from previous: Sort by

If k is the smallest positive integer such that 2,940k

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

Events & Promotions

PREV
NEXT


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®.