It is currently 19 Nov 2017, 09:41

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

another good one!!!!!

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Joined: 04 Apr 2010
Posts: 159

Kudos [?]: 228 [0], given: 31

another good one!!!!! [#permalink]

Show Tags

New post 03 Aug 2010, 16:26
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (02:45) wrong based on 1 sessions

HideShow timer Statistics

What is the probability of creating a three digit number with exactly two consecutive primes as digits?

a) 3/100
b) 9/250
c) 9/125
d) 21/250
e) 51/500

I got this question in this forum unanswered properly and without any OA. Got stuck many times when i try to solve this.
Can anyone help me with this cumbersome problem?
_________________

Consider me giving KUDOS, if you find my post helpful.
If at first you don't succeed, you're running about average. ~Anonymous

Kudos [?]: 228 [0], given: 31

Expert Post
GMAT Tutor
avatar
B
Joined: 24 Jun 2008
Posts: 1339

Kudos [?]: 1998 [0], given: 6

Re: another good one!!!!! [#permalink]

Show Tags

New post 03 Aug 2010, 19:36
bhandariavi wrote:
What is the probability of creating a three digit number with exactly two consecutive primes as digits?

a) 3/100
b) 9/250
c) 9/125
d) 21/250
e) 51/500

I got this question in this forum unanswered properly and without any OA. Got stuck many times when i try to solve this.
Can anyone help me with this cumbersome problem?


This is not a good question. There's no way to tell even what it means, the wording is so poor. The answer choices also make no sense. There are 900 three-digit numbers, so it has to be possible to write the answer as x/900, where x is an integer (x is the number of things with the property we want). No matter what x is, you'll never be able to cancel the fraction x/900 down to any of the answer choices besides A; the denominators in answers B, C, D and E are not factors of 900. Still, no matter how I interpret the question (and I can see several possible legitimate interpretations), the answer is not 3/100. Because the answer choices *can* all be arrived at by canceling a fraction of the form x/1000, I'm guessing the question is not intended to be about 'three digit numbers' at all; instead I imagine it means to ask about numbers from 0 to 999, inclusive. That's not at all clear from the wording.

Then I have no idea just what the phrase "with exactly two consecutive primes as digits" means - this is open to different legitimate interpretations. I assume a number like 302 is one 'with exactly two consecutive primes as digits', since it contains 2 and 3, whereas 325 is not, since it has three consecutive primes as digits. But what about a number like 322? This again contains exactly one pair of consecutive primes, but does not contain exactly two primes. Do we count it? Or perhaps the question means that our number has exactly two consecutive primes as digits and no other digits? So that the only numbers we should count are those like 233, 322, 355, 535, etc? The wording is so ambiguous that solving the question is really testing you psychic abilities - can you guess what the question designer was thinking - and not your GMAT Quant abilities. Just skip it.
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Kudos [?]: 1998 [0], given: 6

Manager
Manager
User avatar
Joined: 04 Apr 2010
Posts: 159

Kudos [?]: 228 [0], given: 31

Re: another good one!!!!! [#permalink]

Show Tags

New post 04 Aug 2010, 15:55
I went through the same trauma.
Thank you!
_________________

Consider me giving KUDOS, if you find my post helpful.
If at first you don't succeed, you're running about average. ~Anonymous

Kudos [?]: 228 [0], given: 31

Re: another good one!!!!!   [#permalink] 04 Aug 2010, 15:55
Display posts from previous: Sort by

another good one!!!!!

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.