|
Author |
Message |
|
SVP
Joined: 16 Nov 2010
Posts: 1721
Location: United States (IN)
Concentration: Strategy, Technology
Followers: 26
Kudos [?]:
228
[0], given: 34
|
The answer is E : (1) 2 is a multiple of itself ( a prime #) (2) 2 is a multiple of 1 and 2
_________________
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
|
Director
Joined: 01 Feb 2011
Posts: 791
Followers: 11
Kudos [?]:
63
[0], given: 42
|
My answer is E. 1. Not sufficient 1*prime =prime 2*prime = not prime 2. Not sufficient Same examples from 1 can be applied here. 1*prime =prime 2*prime = not prime Together it's still not sufficient. Considering Product of two integers also multiple of prime 1*prime =prime 2*prime = not prime Answer is E. Posted from my mobile device 
|
|
|
|
|
|
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2100
Followers: 108
Kudos [?]:
655
[0], given: 376
|
Bunuel wrote: On the GMAT when we are told that a is divisible by b (or which is the same: "a is multiple of b", or "b is a factor of a"), we can say that:
1. a is an integer;
2. b is an integer;
Really!!!! What if a=1.5 and b=1.5; 'a' is divisible by 'b' but 'a' and 'b' are not integers. Can someone clear my doubt because it's highly unlikely that Bunuel will respond?
_________________
~fluke
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Joined: 15 Jul 2010
Posts: 6
Location: Bangkok, Thailand
Followers: 0
Kudos [?]:
10
[0], given: 3
|
E for me Question: If x is an integer, is x a prime number?Statement1: x is a multiple of a prime number --> Insufficient Let's pick x = 2 and 4 If x = 2, 2 is a multiple of 2 (2 x 1), and 2 is a prime number Ans --> Yes If x = 4, 4 is a multiple of 2 (2 x 2), but 4 is NOT a prime number Ans --> No Statement2: x is a product of two integers --> Insufficient Let's pick x =2 and 4 again 2 = 2 x 1 , and 2 is a prime number Ans --> Yes 4 = 4 x 1 , but 4 is NOT a prime number Ans --> No If we take statement#1 together, the given information is still insufficient to determine whether x is a prime number.Let's try x = 2, 4 again 2 is a multiple of a prime number and 2 is a product of two integers (2 x 1 = 2) Ans --> Yes (2 is a prime number) 4 is a multiple of a prime number (2) and 4 is a product of two integers (4 x 1 = 4) Ans --> No (4 is NOT a prime number)
_________________
"You can do it if you believe you can!" - Napoleon Hill
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
|
|
|
|
|
|
Manager
Joined: 11 Jul 2009
Posts: 120
Location: India
WE: Design (Computer Software)
Followers: 1
Kudos [?]:
7
[0], given: 13
|
A....is x a prime number....so according to choice A x is not a prime no and from choice b there can be no conclusion. so correct choice is A
_________________
Kaustubh
|
|
|
|
|
|
Manager
Joined: 25 May 2011
Posts: 171
Followers: 1
Kudos [?]:
17
[0], given: 71
|
mehtakaustubh wrote: A....is x a prime number....so according to choice A x is not a prime no and from choice b there can be no conclusion.
so correct choice is A No. The answer is E. Because based on the S1 you can reach to for example 3, 6, 9, ... 3 is prime but the others are not. So A is insufficient
|
|
|
|
|
|
Intern
Joined: 02 May 2011
Posts: 37
Location: Canada
Concentration: General Management, Social Entrepreneurship
GMAT 1: 630 Q45 V33
GMAT 2: 700 Q47 V40
GPA: 3.78
Followers: 0
Kudos [?]:
7
[0], given: 55
|
seofah wrote: If x is an integer, is x a prime number? 1. x is a multiple of a prime number 2. x is a product of two integers Source: GMAT Club Tests - hardest GMAT questions Statement 1: insufficient Why? 2 is a prime number. 2 x 1 = 2 (and thus a prime number) but 2 x 2 = 4 (not a prime number) Conclusion: insufficient Statement 2: insufficient Why? 2 x 1 = 2 (and thus a prime number) but 2 x 2 = 4 (not a prime number) Conclusion: insufficient Statements 1 & 2: insufficient Why? Same explanation as above. Even with the two statements together, I didn't notice anything new or special from it that I can form. Thus, the same two explanations from above can be used. Conclusion: None of the statements are sufficient to solve the mystery! Answer E.
|
|
|
|
|
|
Intern
Joined: 09 May 2012
Posts: 4
Followers: 0
Kudos [?]:
0
[0], given: 0
|
Why not C
1. multiple of prime.. ok. 3*2... any thing not sufficient
2. product of 2 integer. 3*1, 4*1 no sufficient.
from both,Hello but see, if product of 2 integer, one of them must be 1.
from a. product of a prime. so samalest prime is 2.
so it may me 2*1. 3*1, 5*1.. hense prime.
so answer should be C.
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11628
Followers: 1802
Kudos [?]:
9614
[0], given: 829
|
fluke wrote: Bunuel wrote: On the GMAT when we are told that a is divisible by b (or which is the same: "a is multiple of b", or "b is a factor of a"), we can say that:
1. a is an integer;
2. b is an integer;
Really!!!! What if a=1.5 and b=1.5; 'a' is divisible by 'b' but 'a' and 'b' are not integers. Can someone clear my doubt because it's highly unlikely that Bunuel will respond? Yes. Every GMAT divisibility question will tell you in advance that any unknowns represent positive integers, which means that ALL GMAT divisibility questions are limited to positive integers only. Thus 1.5 is divisible by 1.5 makes no sense as far as GMAT is concerned.
_________________
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory
COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!
DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Status: Rotterdam Erasmus; McGill Desautels UBC Sauder - Admitted
Joined: 28 May 2011
Posts: 22
Schools: ISB, INSEAD, Harvard, Warton
Followers: 0
Kudos [?]:
6
[0], given: 10
|
Paris92978 wrote: Can we revisit this one?
Statement (1) says that x is a multiple of a prime number. Well, that immediately tells us that x is not a prime number because we can factor the a multiple. So now choices B, C, and E are eliminated.
Statement (2) says that x is a product of two integers. Well, we could look at the case of 2 * 3 = 6 but more importantly there is the case of 1 * any prime number. With the case of the 1 * prime number, choice D is eliminated.
Answer is A. Agree with you Paris.. just putting in a bit more inputs.. Case 1: X is a multiple of a prime number -> A number having any factor other than itself and 1 is not a prime no. For example: 6 (1, 2, 3,6) is not a prime no. Please note, that "1" is not a prime number, but rather a co-prime no... so don;t confuse yourself by saying that 7 = 1*7 is a possibility in above case. Option A is sufficientCase 2: X is a product of two integers -> Here there can be two type of number: (i) Prime numbers. Eg. 7 = 1* 7 (ii) Non-prime numbers : 14 = 7 * 2 Not sufficientHence, the answer is (a)
_________________
-- Because beauty Lies in the Eyes.. So donate those eyes 
KUDOS if like the post ... 
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11628
Followers: 1802
Kudos [?]:
9614
[0], given: 829
|
WannabeTitan wrote: Paris92978 wrote: Can we revisit this one?
Statement (1) says that x is a multiple of a prime number. Well, that immediately tells us that x is not a prime number because we can factor the a multiple. So now choices B, C, and E are eliminated.
Statement (2) says that x is a product of two integers. Well, we could look at the case of 2 * 3 = 6 but more importantly there is the case of 1 * any prime number. With the case of the 1 * prime number, choice D is eliminated.
Answer is A. Agree with you Paris.. just putting in a bit more inputs.. Case 1: X is a multiple of a prime number -> A number having any factor other than itself and 1 is not a prime no. For example: 6 (1, 2, 3,6) is not a prime no. Please note, that "1" is not a prime number, but rather a co-prime no... so don;t confuse yourself by saying that 7 = 1*7 is a possibility in above case. Option A is sufficientCase 2: X is a product of two integers -> Here there can be two type of number: (i) Prime numbers. Eg. 7 = 1* 7 (ii) Non-prime numbers : 14 = 7 * 2 Not sufficientHence, the answer is (a)The correct answer s E, not A. If x is an integer, then is x a prime number?(1) x is a multiple of a prime number --> if x=2 then the answer is Yes, but if x=4 then the answer is NO. Not sufficient. (2) x is a product of two integers --> the same here: if x=1*2=2 then the asnwer is Yes, but if x=1*4=4 then the answer is NO. Not sufficient. (1)+(2) The same xample: if x=2 then the asnwer is Yes, but if x=4 then the answer is NO. Not sufficient. Answer: E.
_________________
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory
COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!
DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Intern
Status: Rotterdam Erasmus; McGill Desautels UBC Sauder - Admitted
Joined: 28 May 2011
Posts: 22
Schools: ISB, INSEAD, Harvard, Warton
Followers: 0
Kudos [?]:
6
[0], given: 10
|
Bunuel wrote: WannabeTitan wrote: Paris92978 wrote: Can we revisit this one?
Statement (1) says that x is a multiple of a prime number. Well, that immediately tells us that x is not a prime number because we can factor the a multiple. So now choices B, C, and E are eliminated.
Statement (2) says that x is a product of two integers. Well, we could look at the case of 2 * 3 = 6 but more importantly there is the case of 1 * any prime number. With the case of the 1 * prime number, choice D is eliminated.
Answer is A. Agree with you Paris.. just putting in a bit more inputs.. Case 1: X is a multiple of a prime number -> A number having any factor other than itself and 1 is not a prime no. For example: 6 (1, 2, 3,6) is not a prime no. Please note, that "1" is not a prime number, but rather a co-prime no... so don;t confuse yourself by saying that 7 = 1*7 is a possibility in above case. Option A is sufficientCase 2: X is a product of two integers -> Here there can be two type of number: (i) Prime numbers. Eg. 7 = 1* 7 (ii) Non-prime numbers : 14 = 7 * 2 Not sufficientHence, the answer is (a)The correct answer s E, not A. If x is an integer, then is x a prime number?(1) x is a multiple of a prime number --> if x=2 then the answer is Yes, but if x=4 then the answer is NO. Not sufficient. (2) x is a product of two integers --> the same here: if x=1*2=2 then the asnwer is Yes, but if x=1*4=4 then the answer is NO. Not sufficient. (1)+(2) The same xample: if x=2 then the asnwer is Yes, but if x=4 then the answer is NO. Not sufficient. Answer: E. Bunuel I guess you didn't read the "Please note..." line i mentioned just after the case 1 in my explanation.. In order to emphasize my point that "One" is not a prime number I provide you the following links.. http://primes.utm.edu/notes/faq/one.html http://en.wikipedia.org/wiki/Prime_numberYou will find the common definition of Prime Number as -> "Any number greater than 1 but divisible only by itself and 1 is called a prime number..
_________________
-- Because beauty Lies in the Eyes.. So donate those eyes
KUDOS if like the post ...
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
close
