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

It is currently 22 Oct 2019, 17:59

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

M02-18

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
M02-18  [#permalink]

Show Tags

New post 16 Sep 2014, 00:17
5
31
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

35% (01:50) correct 65% (01:35) wrong based on 325 sessions

HideShow timer Statistics

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re M02-18  [#permalink]

Show Tags

New post 16 Sep 2014, 00:17
3
9
Official Solution:


(1) The product of any three integers in the set is negative. If the set consists of only 3 terms, then the set could be either {negative, negative, negative} or {negative, positive, positive}. If the set consists of more than 3 terms, then the set can only have negative numbers. Not sufficient.

(2) The product of the smallest and largest integers in the set is a prime number. Since only positive numbers can be primes, then the smallest and largest integers in the set must be of the same sign. Thus the set consists of only negative or only positive integers. Not sufficient.

(1)+(2) Since the second statement rules out {negative, positive, positive} case which we had from (1), then we have that the set must have only negative integers. Sufficient.


Answer: C
_________________
Manager
Manager
User avatar
Status: GMAT Date: 10/08/15
Joined: 17 Jul 2014
Posts: 84
Location: United States (MA)
Concentration: Human Resources, Strategy
GMAT 1: 640 Q48 V35
GPA: 3.5
WE: Human Resources (Consumer Products)
Re: M02-18  [#permalink]

Show Tags

New post 07 Apr 2015, 08:27
Bunuel wrote:
Official Solution:


(1) The product of any three integers in the set is negative. If the set consists of only 3 terms, then the set could be either {negative, negative, negative} or {negative, positive, positive}. If the set consists of more than 3 terms, then the set can only have negative numbers. Not sufficient.

(2) The product of the smallest and largest integers in the set is a prime number. Since only positive numbers can be primes, then the smallest and largest integers in the set must be of the same sign. Thus the set consists of only negative or only positive integers. Not sufficient.

(1)+(2) Since the second statement rules out {negative, positive, positive} case which we had from (1), then we have that the set must have only negative integers. Sufficient.


Answer: C


Hello!

I didnt get this one. What if the set has 4 values - 2 positive and 2 negative.

-> [2,3,-1,-5]

Now if we pick any 3 values it can be either positive or negative. e.g 2*3*-1 = -6 but -5*-1*2 - 10

Can you please explain. :oops:

Thanks!
_________________
Thanks,
aimtoteach


~~~~~~~~~~~~~~~~~

Please give Kudos if you find this post useful.
Intern
Intern
avatar
Joined: 07 Apr 2015
Posts: 3
Re: M02-18  [#permalink]

Show Tags

New post 07 Apr 2015, 09:41
2
Bunuel wrote:
Official Solution:


(1) The product of any three integers in the set is negative. If the set consists of only 3 terms, then the set could be either {negative, negative, negative} or {negative, positive, positive}. If the set consists of more than 3 terms, then the set can only have negative numbers. Not sufficient.

(2) The product of the smallest and largest integers in the set is a prime number. Since only positive numbers can be primes, then the smallest and largest integers in the set must be of the same sign. Thus the set consists of only negative or only positive integers. Not sufficient.

(1)+(2) Since the second statement rules out {negative, positive, positive} case which we had from (1), then we have that the set must have only negative integers. Sufficient.


Answer: C



I didn't get it how is it C ?

and the order can be { positive, negative , positive } rite then how is c correct ?
Intern
Intern
avatar
Joined: 05 Feb 2015
Posts: 49
Concentration: Finance, Entrepreneurship
Schools: ISB '16, IIMA , IIMB, IIMC
WE: Information Technology (Health Care)
Re: M02-18  [#permalink]

Show Tags

New post 07 Apr 2015, 10:38
9
Hi appu5
{ positive, negative , positive }
In this case the first condition holds true i.e. product of 3 no's is negative.
Now, lets check he 2nd condition. The product of smallest and largest no. is a prime no.Here smallest would be the negative no. and largest would be one of the positive no., that gives us a negative no.(prime no's are always postiive). So, this example does not satisfy the 2nd condition.
Manager
Manager
User avatar
Joined: 03 Sep 2014
Posts: 75
Concentration: Marketing, Healthcare
Re: M02-18  [#permalink]

Show Tags

New post 07 Apr 2015, 12:04
2
1
aimtoteach wrote:
Bunuel wrote:
Official Solution:


(1) The product of any three integers in the set is negative. If the set consists of only 3 terms, then the set could be either {negative, negative, negative} or {negative, positive, positive}. If the set consists of more than 3 terms, then the set can only have negative numbers. Not sufficient.

(2) The product of the smallest and largest integers in the set is a prime number. Since only positive numbers can be primes, then the smallest and largest integers in the set must be of the same sign. Thus the set consists of only negative or only positive integers. Not sufficient.

(1)+(2) Since the second statement rules out {negative, positive, positive} case which we had from (1), then we have that the set must have only negative integers. Sufficient.


Answer: C


Hello!

I didnt get this one. What if the set has 4 values - 2 positive and 2 negative.

-> [2,3,-1,-5]

Now if we pick any 3 values it can be either positive or negative. e.g 2*3*-1 = -6 but -5*-1*2 - 10

Can you please explain. :oops:

Thanks!



Hi,

It seems you are trying to falsify what is already established in the statement. Statement A states that product of ANY three nos. is negative. Hence we take only those sets of nos. where this condition holds true.

Statement A states that the product of ANY 3 nos. in the set is negative. This can only be true when all the nos. are negative or one or two nos. are positive based on the size of the set. (if it is a three no. set, then two positive nos., for more than 3 no. sets, 1 positive no.) {simply because if there are 3 positive nos., it will hold the Statement A false}. As nos. can be either positive(one or two) or negative, Hence A is not sufficient.

And B states that the product of min and max value is prime. Since only positive nos. can be prime, min and max values should both be either positive or negative. Again B is not sufficient

Thus taking A & C together, both min and max can not be positive since A has already established that all the nos. can not be positive (if min and max are both positive this means all the nos., lie between min and max, will also be positive)
Thus if min and max are both negative, all the nos. are negative which back the inference we made in A.

Hence C is the answer.
Intern
Intern
avatar
B
Joined: 09 Jun 2015
Posts: 1
Re M02-18  [#permalink]

Show Tags

New post 08 Aug 2015, 21:50
2
I think this is a poor-quality question and I don't agree with the explanation. Set (1,-2,3 ) and (-1,-2,-3) can satisfy both conditions
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 17 Aug 2015, 03:23
2
harshada1 wrote:
I think this is a poor-quality question and I don't agree with the explanation. Set (1,-2,3 ) and (-1,-2,-3) can satisfy both conditions


You did not understand the question and the solution.

(2) says: the product of the smallest and largest integers in the set is a prime number.

The product of the smallest and largest integers of (1, -2, 3) is -2*3 = -6, which is not a prime.
_________________
Intern
Intern
avatar
Joined: 22 Jan 2014
Posts: 6
Re M02-18  [#permalink]

Show Tags

New post 13 Sep 2015, 02:03
I think this is a high-quality question and the explanation isn't clear enough, please elaborate. Consider the sets {1,-2, 5} and {-1,-2,-5}. These sets satisfy both St.1 and 2, and so you cannot definitively answer the question. Ans E for me. Not satisfied with the explanation
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 13 Sep 2015, 04:42
1
sidney123 wrote:
I think this is a high-quality question and the explanation isn't clear enough, please elaborate. Consider the sets {1,-2, 5} and {-1,-2,-5}. These sets satisfy both St.1 and 2, and so you cannot definitively answer the question. Ans E for me. Not satisfied with the explanation


You did not understand the question.

(2) says: the product of the smallest and largest integers in the set is a prime number.

The product of the smallest and largest integers of {1, -2, 5} is -2*5 = -10, which is NOT prime!
_________________
Intern
Intern
avatar
Joined: 23 Sep 2015
Posts: 35
Re M02-18  [#permalink]

Show Tags

New post 06 Mar 2016, 08:15
I think this the explanation isn't clear enough, please elaborate. in stat. 2 it doesnt have to mean that all the integers in the set are positive. i can be
-ve +ve -ve
or
+ve -ve +ve (just an example)
we cant say that all the int. have to be of the same sign.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 07 Mar 2016, 10:46
nishantdoshi wrote:
I think this the explanation isn't clear enough, please elaborate. in stat. 2 it doesnt have to mean that all the integers in the set are positive. i can be
-ve +ve -ve
or
+ve -ve +ve (just an example)
we cant say that all the int. have to be of the same sign.


Please read the discussion above.

The smallest integer in your examples above would be negative and the largest one would be positive giving negative product, which cannot be a prime.
_________________
Intern
Intern
avatar
B
Joined: 15 May 2016
Posts: 2
Re M02-18  [#permalink]

Show Tags

New post 25 Jul 2016, 06:41
I think this is a poor-quality question and I don't agree with the explanation. I got the answer as B. The question is are all the integers in the set negative? S2 suggests the smallest and the largest are positive. So all the numbers are not negative. So S2 is sufficient. What am I missing?
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 25 Jul 2016, 08:39
njj1984 wrote:
I think this is a poor-quality question and I don't agree with the explanation. I got the answer as B. The question is are all the integers in the set negative? S2 suggests the smallest and the largest are positive. So all the numbers are not negative. So S2 is sufficient. What am I missing?


Please re-read the solution:
(2) The product of the smallest and largest integers in the set is a prime number. Since only positive numbers can be primes, then the smallest and largest integers in the set must be of the same sign. Thus the set consists of only negative or only positive integers. Not sufficient.
_________________
Intern
Intern
avatar
B
Joined: 21 May 2016
Posts: 7
Re: M02-18  [#permalink]

Show Tags

New post 18 Dec 2016, 21:24
Please elaborate how did you choose option C ? From option B you have concluded that the possibility is only {negative,positive,positive} as prime numbers can only be positive and from option C you have eliminated the same case and choose all numbers to be negative.

Kindly help where I am missing !
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 18 Dec 2016, 23:23
GouthamNandu wrote:
Please elaborate how did you choose option C ? From option B you have concluded that the possibility is only {negative,positive,positive} as prime numbers can only be positive and from option C you have eliminated the same case and choose all numbers to be negative.

Kindly help where I am missing !


From (1): the set could be either {negative, negative, negative} or {negative, positive, positive}.
From (2): the set consists of only negative or only positive integers.

(1)+(2) Since the second statement rules out {negative, positive, positive} case which we had from (1), then we have that the set must have only negative integers.
_________________
Intern
Intern
avatar
B
Joined: 08 May 2017
Posts: 6
Re M02-18  [#permalink]

Show Tags

New post 26 Nov 2017, 12:14
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. (2) The product of the smallest and largest integers in the set is a prime number.

I don´t see how can this actually happen. The set consist of more than two integers, and the only prime number that can be the product of two integers is 2. Therefore, it could be:
- 1 * - 2 = 2 or (-1 being the largest integer and -2 being the smallest)
1 * 2 = 2 (1 being the smallest and 2 being the largest)

However, it says that the set consists of more than two integers.... Please advise
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 26 Nov 2017, 12:22
rperaalv wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. (2) The product of the smallest and largest integers in the set is a prime number.

I don´t see how can this actually happen. The set consist of more than two integers, and the only prime number that can be the product of two integers is 2. Therefore, it could be:
- 1 * - 2 = 2 or (-1 being the largest integer and -2 being the smallest)
1 * 2 = 2 (1 being the smallest and 2 being the largest)

However, it says that the set consists of more than two integers.... Please advise


This could happen VERY easily. Foe example:

{-3, -2, -1} --> The product of the smallest and largest integers in the set = (-3)*(-1) = 3 = prime number.
{-7, -6, -4, -1} --> The product of the smallest and largest integers in the set = (-7)*(-1) = 7 = prime number.
{1, 2, 3, 4, 5, 17} --> The product of the smallest and largest integers in the set = 1*17 = 17 = prime number.
...

Hope now is clear/.
_________________
Intern
Intern
avatar
B
Joined: 13 Apr 2017
Posts: 2
Location: India
Concentration: Leadership, Strategy
WE: Analyst (Advertising and PR)
Re M02-18  [#permalink]

Show Tags

New post 13 Feb 2018, 04:03
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate.
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58427
Re: M02-18  [#permalink]

Show Tags

New post 13 Feb 2018, 05:25
GMAT Club Bot
Re: M02-18   [#permalink] 13 Feb 2018, 05:25

Go to page    1   2    Next  [ 28 posts ] 

Display posts from previous: Sort by

M02-18

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

Moderators: chetan2u, Bunuel






Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne