Manhattan GMAT Challenge - Crack GMAT with one Question Every Week

[Apurv]

We welcome aboard Kevin Fitzgerald from Manhattan GMAT to guide you on cracking GMAT with a Challenge Question Every Week. Kevin has many years of experience helping prospective students push their GMAT scores to the high-end 700+ level. You can read his profile here.

In this thread, Kevin will post a GMAT-like question each Monday based on Data Sufficiency, Problem Solving and Verbal problems. You can discuss the question over the week. Kevin will guide you with tricks and tips all along and post the answer along with the next week's Question the following Monday.

Kevin's profile on Pagaguy.com is this. Good luck!

Also see Ask Manhattan GMAT (Ask Manhattan GMAT).

[KevinFitzgerald]

Most of our students are trying to break the 700+ barrier. As a result, we've developed our own math problems written at the 700+ level; these are the types of questions you'll WANT to see, when you are working at that level. Try to solve this 700+ level Data Sufficiency problem (I'll post the solution next Monday).

Question
What is the positive integer n ?

(1) The sum of all of the positive factors of n that are less than n is equal to n
(2) n < 30

(A) Statement (1) ALONE is sufficient to answer the question, but statement (2) alone is not.
(B) Statement (2) ALONE is sufficient to answer the question, but statement (1) alone is not.
(C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient to answer the question.
(E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question.

[ahmadazeem777]

WOW, Kudos to PG & Manhattan's KevinFitzgerald for this Initiative.... I am sure this will help ppl like me who are preparing for gmat.

Thankx
Azeem

[ahmadazeem777]

Ans is E.

Thankx
Azeem

[iday]

Hey good stuff. This will really be helpful for the ppl who're gonna appear for GMAT.

As someone who's cracked GMAT recently, i'll tag along as well and see how much i can help .

The answer is E from me too.

1. Aint enuf coz there are many numbers. Getting 2 of them will suffice - 6(1+2+3) and 28(1+2+4+7+14) qualify.
2. Aint enuf coz there are 29 numbers between 0 and 30
1 &2 aint enuf coz the same 2 numbers ( 6 and 28 ) are <30.

Hence we cannot pick on a single number and the answer is E.

[ahmadazeem777]

Originally Posted by ahmadazeem777

Ans is E.

Thankx
Azeem

As posted earlier my option choice was E. But to get that I looked at all the numbers from 1 to 30 (excluding primes), which took me 2.5 mts..... So what I am intrested in is a Short Cut for this problem.?????

Thankx
Azeem

[Eccentric001]

ill also go with E.
P.S--this one was to subscribe to this thread..

[amitnsitian]

i will also go with E. there is a special name givento such numbers? whats that???

@eccentric. no need to post if u wanna just subscribe to a thread. click on thread tools on top of the thread and do it from there

[brandslave]

Hi,
Such kind of numbers are known as "Perfect Numbers".
Best
Brandslave

Originally Posted by amitnsitian

i will also go with E. there is a special name givento such numbers? whats that???

@eccentric. no need to post if u wanna just subscribe to a thread. click on thread tools on top of the thread and do it from there

[crazyfootballer]

I'll also go with option E.

From the first statement it is clear that we looking for perfect numbers. There are number of perfect nos. Hence, statement I alone not sufficient.

Statement 2 says, n<30 which again not useful.

Combining both the statements together we get n as 6 and 28. Again, no unique soln. Hence answer is (E).

I say you should remember perfect nos. between 1 and 200 instead of everytime calculating it.