gmat prep question

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 144
Joined: Wed Feb 07, 2007 4:13 pm

gmat prep question

by yvonne12 » Wed Apr 25, 2007 8:41 am
if N denotes a number to the left of 0 on the number line such that the square of N is less than that the square of N is less than 1/100, then the recipricol of N must be

less than -10
between -1 and -1/10
between -1/10 and 0
between 0 and 1/10
greater than 10

explain to me how you interpret this, please

Master | Next Rank: 500 Posts
Posts: 147
Joined: Wed Apr 25, 2007 10:43 am
Location: New York, NY
Thanked: 19 times
Followed by:1 members

by parore26 » Wed Apr 25, 2007 11:07 am
Hi,
Here is how I would solve it:
1) The number is left of 0 on the number line, therefore it's negative.
2) The square is less than 1/100, this implies that the number is a negative fraction.
From 1 & 2 we have that N is a negative fraction. Therefore, the reciprocal of N is also negative. This eliminates choices D & E.
You can eliminate C, if you take reciprocal of N = -1/9 then N = -9 and N^2 > 1/100
You can also eliminate B, -1/2 < -1/10 and -1/2 > -1. The reciprocal is -2 and the square is 4. Therefore the answer is A.

Hope this helps.

Master | Next Rank: 500 Posts
Posts: 144
Joined: Wed Feb 07, 2007 4:13 pm

gmat prep question

by yvonne12 » Wed Apr 25, 2007 4:40 pm
ok , but if its less than -10 would it be the same as the others? I mean squaring any number less than -10 would still make it greater than 1/100 am I missing something here?

or does it mean less than the reciprical of -10

Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

by Cybermusings » Thu Apr 26, 2007 2:04 am
Since the number is to the left of the number line, it is negative and the square of N is less than 1/100
n^2 < 100
Therefore sqr rt of n^2 < sqr rt of 1/100
n<-1/10 (it can't be 1/10...we already know it's negative); so n<-1/10
So reciprocal of n i.e. 1/n < -10
Hence clear choice A

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 7223
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members

by Scott@TargetTestPrep » Mon May 20, 2019 6:22 pm
yvonne12 wrote:if N denotes a number to the left of 0 on the number line such that the square of N is less than that the square of N is less than 1/100, then the recipricol of N must be

less than -10
between -1 and -1/10
between -1/10 and 0
between 0 and 1/10
greater than 10
We are given that N denotes a number to the left of 0 on the number line such that the square of N is less than 1/100. This means N is negative, and it is between 0 and -1/10 since (-1/10)^2 = 1/100. Thus, N could be equal to values such as -1/11, -1/12, -1/13, etc. Notice that when we square these values, they are all less than 1/100.

Let's take the reciprocal of any of these values listed. The reciprocal of -1/11 is -11. Similarly, the reciprocal of -1/12 is -12, and the reciprocal of -1/13 is -13. Since these reciprocals are all less than -10, answer choice A is correct.

Alternate Solution:

Let's find a value for N such that N is negative and the square of N is less than 1/100. If we take N = -1/20, we see that N^2 = 1/400, which is less than 1/100. Now, the reciprocal of N is 1/N = -20, which is less than -10.

Answer: A

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage