Can the positive integer k be expressed as the product . . .

Expert replies

g3lo: Junior | Next Rank: 30 Posts; Posts: 14; Joined: Tue Jan 19, 2016 6:13 pm

by g3lo » Fri Jan 22, 2016 7:36 am

Can the positive integer k be expressed as the product of two integers, each of which is greater than 1?

I am having trouble understanding how this question implies that is K a prime number?

Couldn't the question be asking about a composite number as well? For example, positive integer K implies both composite or prime. Therefore;

4 X 5 = 20 (K)
2 X 6 = 12 (K)

All numbers greater than 1 and K can be expressed as the product of 2 integers, each of which is greater than 1.

What am I missing?

Like this post

Source: Beat The GMAT — Data Sufficiency | Fri Jan 22, 2016 7:36 am

g3lo: Junior | Next Rank: 30 Posts; Posts: 14; Joined: Tue Jan 19, 2016 6:13 pm

by g3lo » Fri Jan 22, 2016 8:28 am

Never mind, I figured it out. Foolish me. It is essentially asking if K is a composite number or non-prime number.

If K = Prime, than you would require a 1 in one of the factors for the product to equal that prime number (k). Therefore, it must be true that the question is relating to a composite number.

Like this post

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Fri Jan 22, 2016 11:47 am

Hi g3lo,

When dealing with DS questions, it might be tempting to take a 'theory-based' approach, but you'll likely find it far more useful to TEST VALUES and assemble 'proof' of what options are available. DS questions 'test' a variety of different skills, including organization, accuracy, attention-to-detail, thoroughness, etc. If you only 'see' one possible outcome, but there is another, then you'll get the question wrong (and you won't even realize it). The 'math' required to answer most DS questions is relatively simple, so don't be afraid of putting the pen on the pad, asking "what if...", and writing down the possibilities.

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Like this post

Matt@VeritasPrep: GMAT Instructor; Posts: 2630; Joined: Wed Sep 12, 2012 3:32 pmFollowed by: 119 members; Location: East Bay all the way; Thanked: 625 times; GMAT Score:780

by Matt@VeritasPrep » Fri Jan 22, 2016 3:42 pm

g3lo wrote:Never mind, I figured it out. Foolish me. It is essentially asking if K is a composite number or non-prime number.

If K = Prime, than you would require a 1 in one of the factors for the product to equal that prime number (k). Therefore, it must be true that the question is relating to a composite number.

Yup, you've got it. Prime numbers can only be expressed as 1 * p, so they can't be expressed as the product of two integers > 1. So the question is asking "Is k a composite integer?" ... which is just the flipside of "Is k prime?"

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review