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

It is currently 22 Sep 2018, 15:51

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

A bowl is filled with consecutively numbered tiles from 1 to x. Joe

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

Hide Tags

Senior Manager
Senior Manager
avatar
Joined: 22 Feb 2004
Posts: 347
A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post Updated on: 13 Jul 2015, 00:48
2
15
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

39% (01:46) correct 61% (02:08) wrong based on 262 sessions

HideShow timer Statistics

A bowl is filled with consecutively numbered tiles from 1 to x. Joe pulls out a tile and uses it to construct Sequence Q, which consists of 10 consecutive integers starting with the number drawn. If Joe then selects one number from Sequence Q, what is the probability that the selected number is a multiple of 3?

(1) The last number in Sequence Q is a prime number that is less than 20.
(2) x <= 10

Originally posted by crackgmat750 on 19 Jul 2004, 21:38.
Last edited by Bunuel on 13 Jul 2015, 00:48, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2004
Posts: 382
Location: Bangalore, India
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 22:19
1
I think it is B.

(1)If Q is less than 20 and a prime number too, then Q can be 19,17,13,11 etc. This gives us different probabilities because of multiples of 3 vary depending on the last prime number.

(2) If x <= 10, then because the sequence consists of 10 integers, it should be between 1 and 10. It has 3,6,9 as multiples of 3. The probability is C(3,1) / C(10,1) = 3/10

What is OA?

crackgmat750 wrote:
A bowl is filled with consecutively numbered tiles from 1 to x. Joe pulls out a tile and uses it to construct Sequence Q, which consists of 10 consecutive integers starting with the number drawn. If Joe then selects one number from Sequence Q, what is the probability that the selected number is a multiple of 3?



(1) The last number in Sequence Q is a prime number that is less than 20.



(2) x<10


I strongly suspect that the answer given is incorrect. I just want to confirm if iam not missing something here.

_________________

Awaiting response,

Thnx & Rgds,
Chandra

CIO
CIO
User avatar
Joined: 09 Mar 2003
Posts: 460
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 22:55
1
3
My answer is A.

We're looking for the number of multiples of three in a list of 10 consecutive numbers. If the list starts with a multiple of three, it will end with a multiple of three, and there will be 4 multiples in the list, making the probability 4/10. If it starts with any other number, the list will have exactly 3 multiples of 3, and the probability will be 3/10. Try a few and you'll see it.

So the question is just to figure out what it starts and ends with.

1) says that the last number is a prime number less than 20. That means it's not a multiple of 3, so there can't be 4 multiples, but there must be 3 multiples. --> sufficient.

2) says the first number is less than or equal to 10. Since that can be anything, multiple of 3 or not, we cannot know --> Insufficient.
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2004
Posts: 382
Location: Bangalore, India
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 23:05
Ian,

Is not D in that case?

(1)What you say is correct as for 1.

(2)If x <= 10 and the sequence consists of 10 tiles, then x = 10 because if x <10, the sequence of 10 tiles cannot be constructed. It means the probability is certain again with 3/10.

Thus both individually suffice to get the answer. Is it not D then?

ian7777 wrote:
My answer is A.

We're looking for the number of multiples of three in a list of 10 consecutive numbers. If the list starts with a multiple of three, it will end with a multiple of three, and there will be 4 multiples in the list, making the probability 4/10. If it starts with any other number, the list will have exactly 3 multiples of 3, and the probability will be 3/10. Try a few and you'll see it.

So the question is just to figure out what it starts and ends with.

1) says that the last number is a prime number less than 20. That means it's not a multiple of 3, so there can't be 4 multiples, but there must be 3 multiples. --> sufficient.

2) says the first number is less than or equal to 10. Since that can be anything, multiple of 3 or not, we cannot know --> Insufficient.

_________________

Awaiting response,

Thnx & Rgds,
Chandra

Senior Manager
Senior Manager
avatar
Joined: 22 Feb 2004
Posts: 347
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 23:11
mallelac wrote:
Ian,

Is not D in that case?

(1)What you say is correct as for 1.

(2)If x <= 10 and the sequence consists of 10 tiles, then x = 10 because if x <10, the sequence of 10 tiles cannot be constructed. It means the probability is certain again with 3/10.

Thus both individually suffice to get the answer. Is it not D then?

ian7777 wrote:
My answer is A.

We're looking for the number of multiples of three in a list of 10 consecutive numbers. If the list starts with a multiple of three, it will end with a multiple of three, and there will be 4 multiples in the list, making the probability 4/10. If it starts with any other number, the list will have exactly 3 multiples of 3, and the probability will be 3/10. Try a few and you'll see it.

So the question is just to figure out what it starts and ends with.

1) says that the last number is a prime number less than 20. That means it's not a multiple of 3, so there can't be 4 multiples, but there must be 3 multiples. --> sufficient.

2) says the first number is less than or equal to 10. Since that can be anything, multiple of 3 or not, we cannot know --> Insufficient.


Exactly..that's what I feel and think answer should be D. But the answer given is A.
CIO
CIO
User avatar
Joined: 09 Mar 2003
Posts: 460
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 23:14
No, it's A. You're reading the question wrong. x is the last number is the bowl that this dude is pulling his numbers out of. But once he pulls out the first number, Q is built by finding the next 9 consecutive numbers.

So if guy pulls out a 3, then Q will be 3,4,5,6,7,8,9,10,11,12. If he pulls out a 5, Q will be 5,6,7,8,9,10,11,12,13,14.

So x doesn't have to do with the number of numbers in Q, nor is it the last number in Q. It's actually the highest limit of what the first number of Q could be.

Does that make sense?
Senior Manager
Senior Manager
avatar
Joined: 22 Jun 2004
Posts: 382
Location: Bangalore, India
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 19 Jul 2004, 23:23
1
Yes Ian, it makes sense now.
8-) 8-)

ian7777 wrote:
No, it's A. You're reading the question wrong. x is the last number is the bowl that this dude is pulling his numbers out of. But once he pulls out the first number, Q is built by finding the next 9 consecutive numbers.

So if guy pulls out a 3, then Q will be 3,4,5,6,7,8,9,10,11,12. If he pulls out a 5, Q will be 5,6,7,8,9,10,11,12,13,14.

So x doesn't have to do with the number of numbers in Q, nor is it the last number in Q. It's actually the highest limit of what the first number of Q could be.

Does that make sense?

_________________

Awaiting response,

Thnx & Rgds,
Chandra

Manager
Manager
User avatar
Joined: 15 Apr 2016
Posts: 81
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 12 Sep 2016, 11:43
Actually for the second statement ...
(2) x <= 10

consider x =10 and i pick up 3 - 3,4,5,6,7,8,9,10,11,12 - i have 4 multiples of 3 (3,6,9,12) -prob - 4/10
Consider i pick 4 - 4,5,6,7,8,9,10,11,12,13 - i have 3 multiples of 3(6,9,12)- prob -3/10

since there are 2 results ..A is the answer
_________________

Cheers,
Shri
-------------------------------
GMAT is not an Exam... it is a war .. Let's Conquer !!!

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8153
Premium Member
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe  [#permalink]

Show Tags

New post 21 Aug 2018, 20:22
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

GMAT Club Bot
Re: A bowl is filled with consecutively numbered tiles from 1 to x. Joe &nbs [#permalink] 21 Aug 2018, 20:22
Display posts from previous: Sort by

A bowl is filled with consecutively numbered tiles from 1 to x. Joe

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

Events & Promotions

PREV
NEXT


Copyright

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®.