Is 100 in K?

Expert replies

Sunshine85: Junior | Next Rank: 30 Posts; Posts: 19; Joined: Tue Mar 31, 2009 11:38 pm; Thanked: 2 times

by Sunshine85 » Sun May 10, 2009 1:53 am

Q) K is a set of integers such that if the integer r is in K, then r + 1 is also in K. Is 100 in K?

(1) 50 is in K.
(2) 150 is in K.

The Answer is E.... But How?

Like this post

Source: Beat The GMAT — Data Sufficiency | Sun May 10, 2009 1:53 am

Vemuri: Legendary Member; Posts: 682; Joined: Fri Jan 16, 2009 2:40 amFollowed by: 1 member; Thanked: 32 times

Re: Is 100 in K?

by Vemuri » Sun May 10, 2009 5:04 am

I don't think the answer is E. It should be A. Let me explain.

The question stem says that if integer r is in K, then r+1 is also in K.

Stmt1: If 50 is in K, the 51 is also in K. If 51 is in K, then 52 is also in K.....and so on...until 99 is in K. If 99 is in K, then 100 also in K.......it goes on. So, this statement is sufficient to answer the question that 100 is in K.

Stmt2: If 150 is in K, the 151 is in K.......and so on upwards. This statement will not help us determine if 100 is in K. So, insufficient.[/b]

Like this post

Sunshine85: Junior | Next Rank: 30 Posts; Posts: 19; Joined: Tue Mar 31, 2009 11:38 pm; Thanked: 2 times

by Sunshine85 » Sun May 10, 2009 8:52 pm

Thanks Mr. Vemuri

Like this post

tdadic84: Master | Next Rank: 500 Posts; Posts: 111; Joined: Sat Sep 27, 2008 12:41 pm; Thanked: 1 times

by tdadic84 » Mon May 11, 2009 10:37 am

vemuri,

But A does not mention how many integers are in K...what if it goes to 61 + 1 and then stops?? then 100 would not be in K, it does not tell us how many numbers are in the set...

am i missing something?

Like this post

splendentsky: Newbie | Next Rank: 10 Posts; Posts: 4; Joined: Mon May 11, 2009 10:32 am; Location: NY

by splendentsky » Mon May 11, 2009 12:13 pm

I think E is the answer because not enough information was given.

Like this post

Sunshine85: Junior | Next Rank: 30 Posts; Posts: 19; Joined: Tue Mar 31, 2009 11:38 pm; Thanked: 2 times

by Sunshine85 » Mon May 11, 2009 9:27 pm

Don u think if 50 is in K, 51 is in K?

if so 52 is also in K and this goes on.....

So I go with Vemuri.

Any further comments are welcome.

Like this post

DanaJ: Site Admin; Posts: 2567; Joined: Thu Jan 01, 2009 10:05 amFollowed by: 550 members; Thanked: 712 times; GMAT Score:770

by DanaJ » Tue May 12, 2009 2:37 am

This topic has been discussed before. See Stuart's example for clarifications:

https://www.beatthegmat.com/ds-doubt-t35181.html

Like this post

criszerriny: Junior | Next Rank: 30 Posts; Posts: 19; Joined: Mon Apr 20, 2009 2:25 pm

by criszerriny » Wed May 13, 2009 9:26 am

Keep in mind, the question is about a set of integers, so it must be A since B would make it infinite.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 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