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.
It appears that you are browsing the GMAT Club forum unregistered!
Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club
Registration gives you:
Tests
Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.
Applicant Stats
View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more
Books/Downloads
Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
This is the answer in the book but I just don't get it..
Statement (1) tells us that there are x unique factors of x. In order for this to be true, EVERY integer between 1 and x, inclusive, must be a factor of x. Testing numbers, we can see that this property holds for 1 and for 2, but not for 3 or for 4. In fact, this property does not hold for any higher integer, because no integer x above 2 is divisible by x-I. Therefore, x = 1 or 2. However, the original problem stem told us that x > 1, so x must equal 2. SUFFICIENT. Statement (2) tells us that x plus any prime number larger than x is odd. Since x > 1, x must equal at least 2, so this includes only prime numbers larger than 2. Therefore, the prime number is odd, and x is even. However, this does not tell us which even number x could be. INSUFFICIENT. The correct answer is (A): Statement (1) is sufficient to answer the ques- tion, but Statement (2) is insufficient.
Re: If x > 1, what is the value ofinteger x? [#permalink]
18 Mar 2011, 13:39
even i was confuse for the first time. But I think the answer explainations tells, if say x = 5, then it needs 5 unique factor, but for 5 it is only 1 and 5. For 4 it is 1,2, and 4. So for any number greater than 2 there is no way you can have as many factor as the number itself. hence it should be 2. I hope I interpreted right, but as I said it is a confusing question.
Re: If x > 1, what is the value ofinteger x? [#permalink]
18 Mar 2011, 14:34
1
This post received KUDOS
Well here is how i would do it.
1. x has x factors
meaning if you take any integer , that should have that many factors
1 has 1 factor (i.e 1 , meets the criteria) 2 has 2 factors (i.e 1 and 2) 3 has 2 factors (i.e 1 and 3, doesnt meet the criteria, to satisfy this should have had 3 factors)
take any other number lets say 17 , to meet this criteria this should have 17 factors. not satisfied.
so only 1 and 2 satisfies the condition, then again in the question it says x has to be greater than 1 . so that rules out 1 . Hence x =2 .
So sufficient. 2. x + ( prime >x )has to be odd
primes (2,3,5,7,11....)
2+ (prime >2) = 2 +3 = odd (x could be 3) 2+5 = odd (x could be 5)
Not sufficient as there are more possible values for x.
Re: If x > 1, what is the value ofinteger x? [#permalink]
18 Mar 2011, 18:13
3
This post received KUDOS
Expert's post
l0rrie wrote:
If x > 1, what is the value of integer x?
(1) There are x unique factors of x. (2) The sum of x and any prime number larger than x is odd.
First of all, it is not a very straight forward question. Definitely needs some thinking so relax...
Ques: What is the value of x? So we are looking for a single value of x.
First consider statement 2 since it is easier. x + prime number greater than x = odd There will be many many prime numbers greater than x. All prime numbers are odd except 2. So if you can add any prime number greater than x to x and get an odd number, it means x must be even. (because Even + Odd = Odd) So all statement 2 tells you is that x is even. It could be 2 or 4 or 6 etc
Now look at statement 1. There are x unique factors of x. Think of the first number greater than 1. 2 has 2 unique factors: 1 and 2 ( 2 is a prime number) What about 3? It has 2 unique factors: 1 and 3 (a prime number) 4 has 3 unique factors: 1, 2 , 4 Is it possible that any greater number x has x unique factors? No. Why? For x to have x unique factors, each number from 1 to x must be a factor of x. Say if 10 had 10 unique factors, each number 1, 2, 3, 4, 5..., 9,10 would have to be a factor of 10 (because factors are always positive integers) But can 9 be a factor of 10 i.e. can (x-1) be a factor of x? No. 2 consecutive positive integers share only one common factor i.e. 1. Why? Check out the post given below for the answer: question-from-practice-exam-78880.html#p847817
So statement 1 is enough to tell us that x is 2. _________________
Re: If x > 1, what is the value ofinteger x? [#permalink]
19 Mar 2011, 02:34
Thanks everyone!! Really much appreciated, I get it now.. This has been extremely helpful.. I need to do a GMAT but it's been 6 years since I've studied maths.. And even in high school I was horrible so i'm really stressed about this.. Hopefully I'll get better haha.. Again, thanks!
Re: If x > 1, what is the value ofinteger x? [#permalink]
19 Sep 2013, 13:37
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. _________________
Re: If x > 1, what is the value of integer x? [#permalink]
19 Sep 2013, 23:34
Expert's post
1
This post was BOOKMARKED
If x>1, what is the value of integer x?
(1) There are x unique factors of x --> x to have x distinct positive factors it must be divisible by EVERY integer from 1 to x, inclusive but x can not be divisible by x-1 unless x=2, for example 3 is not divisible by 2, 4 is not divisible by 3, etc, but 2 is divisible by 1 (other value of x which has x distinct positive factors (1) is excluded by the stem as x>1). So this statement implies that x=2. Sufficient.
(2) The sum of x and any prime number larger than x is odd --> x+prime=odd, now as x itself is more than 1 then prime more than x cannot be 2 thus it's odd and we have x+odd prime=odd --> x=even, so x could be ANY even number. Not sufficient.
As I’m halfway through my second year now, graduation is now rapidly approaching. I’ve neglected this blog in the last year, mainly because I felt I didn’...
Perhaps known best for its men’s basketball team – winners of five national championships, including last year’s – Duke University is also home to an elite full-time MBA...
Hilary Term has only started and we can feel the heat already. The two weeks have been packed with activities and submissions, giving a peek into what will follow...