Page 1 of 1 [ 2 posts ]
 Print view Previous topic | Next topic
Author Message
 Post subject: Prep Test Question #5Posted: Sat Jul 23, 2011 6:34 pm

Joined: Thu Feb 10, 2011 11:12 pm
Posts: 10

This is a GMAT Prep Test question - Data Sufficency.

I thought the answer was E) Neither sufficient alone or together. The correct answer however is: A) Statement 1 is sufficient. Please explain how as my thoughts were:

If for example k = 2 or -2 (since it doesn't specify k is positive)

st1) 1/(2-1) > 0 yes, but 1/(-2-1) < 0 ----------Thus NS
st2) 1/(2+1) > 0 yes, but 1/(-2+1) < 0 -------------Thus NS

And together, I thought they weren't sufficient.

Top

 Post subject: Re: Prep Test Question #5Posted: Wed Jul 27, 2011 6:07 pm

Joined: Thu May 06, 2010 3:17 pm
Posts: 28
Location: Everywhere
Statement 1 tells us that 1/(k-1) is greater than 0. Since the statements are absolute fact, any value of k that doesn't fit that inequality is not a valid possibility for k. Any negative number would leave us with a negative denominator, which doesn't work. Based on that and the values ruled out in the question itself, k must be positive, and 1 divided by a positive number is always positive. Sufficient.

For statement 2, we need to remember that k doesn't have to be an integer. If we plug in k=-.5, we get:

1/(-.5+1) > 0

1/.5 >0

2>0

So k=-.5 is valid. When we plug into the question, 1/-.5 is not greater than 0, which is a definitive no. For any positive value of k, we'd get a definitive yes, so, as a whole, we don't know. Insufficient.

Bill

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 2 posts ]

 All times are UTC - 8 hours [ DST ]

#### Who is online

Users browsing this forum: nourneJoineed and 1 guest

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

 Search for: