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

 It is currently 17 Jul 2018, 14:31

### 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

# prime numbers...........

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
Manager
Joined: 02 Sep 2008
Posts: 102

### Show Tags

06 Apr 2009, 01:57
00:00

Difficulty:

(N/A)

Question Stats:

100% (01:47) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

Attachment:
File comment: untitled

untitled.JPG [ 14.53 KiB | Viewed 1817 times ]

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Senior Manager
Joined: 01 Mar 2009
Posts: 349
Location: PDX
Re: prime numbers........... [#permalink]

### Show Tags

06 Apr 2009, 08:18
so p^2q^2 = 5(x)

Since both p and q are prime. q has to be 5 for this equation to be true.

so p^2 * 5 = 5(x)

So what is a multiple of 25 or 5^2(x) .

p^2 * 5 * 5 = 5*5(x)

= p^2q^2 ( since q = 5 )

_________________

In the land of the night, the chariot of the sun is drawn by the grateful dead

VP
Joined: 28 Dec 2005
Posts: 1482
Re: prime numbers........... [#permalink]

### Show Tags

06 Apr 2009, 18:39
pbanavara wrote:
so p^2q^2 = 5(x)

where did you get that from ?
Senior Manager
Joined: 01 Mar 2009
Posts: 349
Location: PDX
Re: prime numbers........... [#permalink]

### Show Tags

06 Apr 2009, 23:16
pmenon wrote:
pbanavara wrote:
so p^2q^2 = 5(x)

where did you get that from ?

oops I meant p^2q = 5(x) From the question stem
_________________

In the land of the night, the chariot of the sun is drawn by the grateful dead

Manager
Joined: 02 Mar 2009
Posts: 122
Re: prime numbers........... [#permalink]

### Show Tags

06 Apr 2009, 23:36
n = 5k. (n is a multiple of 5)
n = p^2.q (Where p and q are prime numbers)

This means, either p or q is 5 because n is a multiple of 5 afterall. NOTE: It can be EITHER of them.
Now we want multiple of 25 which is equal to 5^2. Thus:
Q = 5^2 . z (We need to find the multiple Q where z is a constant)

Now look at the options:
Can Q equal p^2? It could but we are not sure that p=5.
Can Q equal q^2? It could but we are not sure that q=5.
Can Q equal pq? No because we need 5 at least with an exponent of 2.
Can Q equal p^2q^2? YES. At least one of them is 5^2!!
Can Q equal p^3q? Again, what if q=5? In that case, we will be lacking one exponent of 5

Hence D it is
Hope this helps.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: prime numbers...........   [#permalink] 06 Apr 2009, 23:36
Display posts from previous: Sort by

# prime numbers...........

 post reply Question banks Downloads My Bookmarks Reviews Important topics

Moderators: chetan2u, KarishmaB, niks18, Bunuel

# 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®.