Find all School-related info fast with the new School-Specific MBA Forum

It is currently 30 Aug 2015, 10:24
GMAT Club Tests

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If p, s, and t are positive prime numbers, what is the value

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
2 KUDOS received
Senior Manager
Senior Manager
avatar
Joined: 12 Mar 2009
Posts: 318
Followers: 1

Kudos [?]: 138 [2] , given: 1

GMAT ToolKit User
If p, s, and t are positive prime numbers, what is the value [#permalink] New post 22 Jan 2010, 23:18
2
This post received
KUDOS
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

60% (02:17) correct 40% (01:34) wrong based on 85 sessions
If p, s, and t are positive prime numbers, what is the value of p^3s^3t^3?

(1) (p^3)*s*t=728
(2) t=13
[Reveal] Spoiler: OA
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 29148
Followers: 4729

Kudos [?]: 49813 [0], given: 7496

Re: cubes_Math set24 [#permalink] New post 23 Jan 2010, 00:47
Expert's post
1
This post was
BOOKMARKED
vaivish1723 wrote:
2
if p, s, and t are positive prime numbers, what is the value of p^3s^3t^3?
(1) p^3st=728
(2) t=13

OA is
[Reveal] Spoiler:
a


Question: \(p^3*s^3*t^3\)?

(1) \(728=2^3*7*13=p^3*s*t\) --> as all variables are prime numbers then \(p\) must be \(2\), and \(s\) and \(t\) either \(7\) and \(13\) or \(13\) and \(7\) respectively. In either of cases we can calculate \(p^3*s^3*t^3\). Sufficient.

(2) \(t=13\), clearly insufficient.

Answer: A.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis ; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) ; 12. 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?
25 extra-hard Quant Tests

GMAT Club Premium Membership - big benefits and savings

Manager
Manager
avatar
Joined: 26 Nov 2009
Posts: 176
Followers: 3

Kudos [?]: 53 [0], given: 5

GMAT ToolKit User
Re: cubes_Math set24 [#permalink] New post 23 Jan 2010, 09:35
I got this one wrong I was trying to solve algebraically so went for E
Current Student
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2798
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 201

Kudos [?]: 1216 [0], given: 235

Reviews Badge
Re: cubes_Math set24 [#permalink] New post 26 Jan 2010, 09:09
Nice.

I thought both together are sufficient...
This was trapy.
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

GMAT Club Premium Membership - big benefits and savings

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

Director
Director
avatar
Status: Matriculating
Affiliations: Chicago Booth Class of 2015
Joined: 03 Feb 2011
Posts: 925
Followers: 13

Kudos [?]: 245 [0], given: 123

Reviews Badge
Re: If p, s, and t are positive prime numbers, what is the value [#permalink] New post 01 Mar 2011, 09:54
Q Can be rephrased as what is p*q*r?

1) Sufficient
728 = 2^3 * 7 * 13. Hence prime numbers are 2,7,13.

2) Insufficient.
Manager
Manager
avatar
Joined: 14 Feb 2011
Posts: 196
Followers: 4

Kudos [?]: 81 [0], given: 3

Re: If p, s, and t are positive prime numbers, what is the value [#permalink] New post 01 Mar 2011, 09:54
From 1, 728 can be written as\(2^3*13*7\) , so the only combination possible is p=2 and st = 13*7 hence \(p^3*s^3*t^3\)= \(2^3*13^3*7^3\) Sufficient

From 2, t = 13 but we do not know anything about p or s, so insufficient.

Answer A
Manager
Manager
avatar
Joined: 08 Oct 2010
Posts: 213
Location: Uzbekistan
Schools: Johnson, Fuqua, Simon, Mendoza
WE 3: 10
Followers: 9

Kudos [?]: 380 [0], given: 974

Re: 2 if p, s, and t are positive prime numbers, what is the [#permalink] New post 01 Mar 2012, 02:44
vaivish1723 wrote:
2
if p, s, and t are positive prime numbers, what is the value of p^3s^3t^3?
(1) p^3st=728
(2) t=13

OA is
[Reveal] Spoiler:
a


Bunuel's approach is very good, but let's apply a slightly different approach:
1) p^3st=728

st=728/(p^3) --> here we have to pay attention that the last digit of 728 is 8 which is contained only in the cyclicity of 2 and 8. Lets clarify it:
the cyclicity of 1, 5, 6 are these numbers themselves (regardless of their power)
the cyclicity of 2: 2, 4, 8, 6
the cyclicity of 3: 3, 9, 7, 1
the cyclicity of 4: 4, 6
the cyclicity of 7: 7, 9, 3, 1
the cyclicity of 8: 8, 4, 2, 6
the cyclicity of 9: 9, 1


Hence, 728 is divisible either by 2 or 8.
2^3 = 8 and 8^3 = 512

As you see, 728 is divisible only by 2^3 provided p is a positive prime number.

The result is 728/(2^3) = 91

s × t = 91 can be written as 1 × 91 or 13 × 7. As to the original question p^3 × s^3 × t^3 it does not matter whether we assume s × t is 1 × 91 or vice versa the same is true in case of 13 × 7.

both conditions s × t = 1 × 91 and s × t = 13 × 7 satisfy stmt 1)
because 2^3 × 1 × 91 and 2^3 × 13 × 7 yield 728

Thus, we get the same result regardless whether p^3 × s^3 × t^3 is written as either 2^3 × 1^3 × 91^3 or 2^3 × 13^3 × 7^3

stmt 2) is obviously not sufficient.

Hope, it helps.
SVP
SVP
User avatar
Joined: 06 Sep 2013
Posts: 2046
Concentration: Finance
GMAT 1: 770 Q0 V
Followers: 32

Kudos [?]: 342 [0], given: 355

GMAT ToolKit User
Re: If p, s, and t are positive prime numbers, what is the value [#permalink] New post 15 Oct 2013, 07:59
vaivish1723 wrote:
If p, s, and t are positive prime numbers, what is the value of p^3s^3t^3?

(1) (p^3)*s*t=728
(2) t=13


Just to touch on some key points on this problem.
This problem is meant to test prime factorization.

So we need to break 728 into primes first.
This will give us (2^3) (13) (7) which is enough to solve the question.

Keep in mind some properties of primes and prime factorization

- All prime numbers except 2 and 5 end in '1','3','7' or '9'
- All prime numbers above 3 are of the form '6n+1' or '6n-1'
- The first prime number is 2 which is also the only even prime
- The Prime Numbers up to 100 are: 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97)
- The square of any prime number greater than 3 is 1 more than a multiple of 12
- Verifying the primality of a given number 'n' can be done by trial division, that is to say dividing 'n' by all integer numbers smaller than √n

Hope this helps for future questions
Cheers!

J :)
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 6114
Followers: 341

Kudos [?]: 70 [0], given: 0

Premium Member
Re: If p, s, and t are positive prime numbers, what is the value [#permalink] New post 29 Jul 2015, 00:22
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.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: If p, s, and t are positive prime numbers, what is the value   [#permalink] 29 Jul 2015, 00:22
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic Is the positive integer P a prime number? alphonsa 4 18 Aug 2014, 06:59
10 Experts publish their posts in the topic If p is a positive integer, is p a prime number? Bunuel 9 06 Jun 2014, 05:29
2 Experts publish their posts in the topic If p is a prime number, what is the value of p ? (1) \sqrt Bunuel 16 03 Oct 2010, 09:30
8 Experts publish their posts in the topic If p is a prime number greater than 2, what is the value of aljatar 14 28 Mar 2010, 04:56
4 Experts publish their posts in the topic If p is a prime number greater than 2, what is the value of 700orbust 9 12 Jul 2008, 14:46
Display posts from previous: Sort by

If p, s, and t are positive prime numbers, what is the value

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

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®.