Mar 27 03:00 PM PDT  04:00 PM PDT Join a free live webinar and learn the winning strategy for a 700+ score on GMAT & the perfect application. Save your spot today! Wednesday, March 27th at 3 pm PST Mar 29 06:00 PM PDT  07:00 PM PDT Join a FREE 1day workshop and learn how to ace the GMAT while keeping your fulltime job. Limited for the first 99 registrants. Mar 29 10:00 PM PDT  11:00 PM PDT Right now, their GMAT prep, GRE prep, and MBA admissions consulting services are up to $1,100 off. GMAT (Save up to $261): SPRINGEXTRAGMAT GRE Prep (Save up to $149): SPRINGEXTRAGRE MBA (Save up to $1,240): SPRINGEXTRAMBA Mar 30 07:00 AM PDT  09:00 AM PDT Attend this webinar and master GMAT SC in 10 days by learning how meaning and logic can help you tackle 700+ level SC questions with ease. Mar 31 07:00 AM PDT  09:00 AM PDT Attend this webinar to learn a structured approach to solve 700+ Number Properties question in less than 2 minutes.
Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 53831

If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 01:49
Question Stats:
45% (02:15) correct 55% (01:39) wrong based on 146 sessions
HideShow timer Statistics
GMAT CLUB'S FRESH CHALLENGE QUESTION: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2} If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer? A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 21/49
Official Answer and Stats are available only to registered users. Register/ Login.
_________________



Intern
Joined: 05 Mar 2015
Posts: 45
Location: Azerbaijan
GMAT 1: 530 Q42 V21 GMAT 2: 600 Q42 V31 GMAT 3: 700 Q47 V38

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 03:49
I think answer is A
There are 7x7=49 possible products
And 8 oh them yield negative integers
1) 10x1/5 2) 10x1/2 3) 9x1/3 4) 8x1/2 5) 6x1/3 6) 6x1/2 7) 5x1/5 8) 4x1/2



Intern
Joined: 02 Mar 2017
Posts: 11

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 05:08
A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2}
If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer?
A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 24/49  Total number of ways is 7*7 =49
Number of ways to select 1 number from A > 7C1 >7 For the product to be negative select a positive number from B > no.of ways > 3c1  >3
Total possibility  > 7 *3  21
Probability is 21/49
But i am not able to find the answer in the question stem



Intern
Joined: 05 Mar 2015
Posts: 45
Location: Azerbaijan
GMAT 1: 530 Q42 V21 GMAT 2: 600 Q42 V31 GMAT 3: 700 Q47 V38

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 05:25
Munch wrote: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2}
If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer?
A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 24/49  Total number of ways is 7*7 =49
Number of ways to select 1 number from A > 7C1 >7 For the product to be negative select a positive number from B > no.of ways > 3c1  >3
Total possibility  > 7 *3  21
Probability is 21/49
But i am not able to find the answer in the question stem ]The question specifically asks for integers,



Intern
Joined: 02 Mar 2017
Posts: 11

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 05:30
kablayi wrote: Munch wrote: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2}
If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer?
A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 24/49  Total number of ways is 7*7 =49
Number of ways to select 1 number from A > 7C1 >7 For the product to be negative select a positive number from B > no.of ways > 3c1  >3
Total possibility  > 7 *3  21
Probability is 21/49
But i am not able to find the answer in the question stem ]The question specifically asks for integers, Oh ya!! thanks!! then it should be 8 .. I doubled checked the possibility to match the answer, but still missed the word integer..



Manager
Joined: 05 Oct 2014
Posts: 51
Location: India
Concentration: General Management, Strategy
GPA: 3.8
WE: Project Management (Energy and Utilities)

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 06:28
A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2}
I am not sure whether we should consider the product numbers of ‘0’.
Considering ‘0’ as an eligible possibility, A X B will be ve when, either A or B is ve. Since all values for A is ve, then all values of B must be +ve. In such case, only pairs will be ve when value of B is 1/5 , 1/3 or 1/2. For each A, there will be 3 Negative Values, i.e A X B = 10*1/5 = 10/5 ; 10/3 ; 10/2 = 9/5 ; 9/3 ; 9/2 . . . and so on.
Thus possible negative values will be = 7*3 =21
Total Possible product values will be = 7*7=49
Thus P(E) = 21/49. Option E is right.



Intern
Joined: 29 Sep 2017
Posts: 1

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 07:04
The question specifically asks for ve integers("0" is not a ve integer). Now Set A has only ve integers so we have to select only +ve fractions from set B i.e.{1/5,1/3,1/2}. With 1/5 we can only select 10 & 5 from set A. So possible combinations : 1/5*10 & 1/5*5. Number of possible combinations = 2
With 1/3 we can only select 9 & 6 from set A. Number of possible combinations = 2 With 1/2 we can only select 10,8,6,4 from set A. Number of possible combinations = 4 Thus we have 2+2+4 = 8 combinations Total Possible combinations = 7C1 * 7C1 = 49 Ans = 8/49



Math Expert
Joined: 02 Aug 2009
Posts: 7446

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 17:57
Bunuel wrote: GMAT CLUB'S FRESH CHALLENGE QUESTION: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2} If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer? A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 21/49 Since we are looking for negative integer, we have to consider only POSITIVE numbers in set B as all are NEGATIVE in set A.. 1) 1/2 This will give integers when multiplied by MULTIPLE of 2 So 4,6,8,10......4ways 2) 1/3 Similarly when multiplied by MULTIPLE of 3 6,9.....2ways 3) 1/5 When multiplied by MULTIPLE of 5 So 5,10.....2ways Total  4+2+2=8ways Possible products = 7*7=49 Ans 8/49 A
_________________



Manager
Joined: 05 Oct 2014
Posts: 51
Location: India
Concentration: General Management, Strategy
GPA: 3.8
WE: Project Management (Energy and Utilities)

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
13 Dec 2017, 19:59
chetan2u wrote: Bunuel wrote: GMAT CLUB'S FRESH CHALLENGE QUESTION: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2} If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer? A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 21/49 I missed the INTEGER PART Since we are looking for negative integer, we have to consider only POSITIVE numbers in set B as all are NEGATIVE in set A.. 1) 1/2 This will give integers when multiplied by MULTIPLE of 2 So 4,6,8,10......4ways 2) 1/3 Similarly when multiplied by MULTIPLE of 3 6,9.....2ways 3) 1/5 When multiplied by MULTIPLE of 5 So 5,10.....2ways Total  4+2+2=8ways Possible products = 7*7=49 Ans 8/49 A



Math Expert
Joined: 02 Sep 2009
Posts: 53831

Re: If a number is to be randomly selected from set A above and a number
[#permalink]
Show Tags
24 Dec 2018, 04:52
Bunuel wrote: GMAT CLUB'S FRESH CHALLENGE QUESTION: A = {10, 9, 8, 7, 6, 5, 4} B = {1/2, 1/3, 1/5, 0, 1/5, 1/3, 1/2} If a number is to be randomly selected from set A above and a number is to be randomly selected from set B above, what is the probability that the product of the two numbers will be a negative integer? A. 8/49 B. 12/49 C. 13/49 D. 18/49 E. 21/49 Par of GMAT CLUB'S New Year's Quantitative Challenge Set
_________________




Re: If a number is to be randomly selected from set A above and a number
[#permalink]
24 Dec 2018, 04:52






