Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: One number, n, is selected at random from a set of 10 intege [#permalink]
05 May 2013, 21:52

Both statements seem quite ambiguous considering that we are dealing with a set of random integers. We essentially need the probability of N = 26 Statement 1 : there may be any number of integers less than 13 the set could consist of 9, -26's and one 13 or one -26, 13 and eight other integers Statement 2 : The set could have any 5 negative numbers and the same numbers in positive as well making the average 0. The statement can in no way specify exactly how many times -26 appears in the set.

Both statements taken together also cannot conclusively give the no. of times -26 appears in the set. If -26 appears once in the set it could be offset in the average by 13, 12 & 1. 2 nos. of 26 similarly could be offst in the average by 13,12,11,10,6.

SO E

_________________

When you feel like giving up, remember why you held on for so long in the first place.

Last edited by aceacharya on 05 May 2013, 22:02, edited 1 time in total.

Re: One number, n, is selected at random from a set of 10 intege [#permalink]
05 May 2013, 21:53

Expert's post

rajatr wrote:

One number, n, is selected at random from a set of 10 integers. What is the probability that ½ n + 13 = 0 ?

1 .The largest integer in the set is 13. 2. The arithmetic mean of the set is zero.

For n/2+13 = 0, n = -26.

From F.S 1, we have the largest integer as 13. Thus the set could have all 10 positive integers including 13 in which case the probability - 0. Also, the number -26 could be included in some other combinations of 10 integers, where the probability would be a non-zero entity. Insufficient.

From F.S 2, as the arithmetic mean of the set is zero, hence the sum of all the ten integers is zero. Again, the presence/absence of -26 is not ascertained from this fact statement.Insufficient.

Combining both, for set -26,-5,-3,-2,0,2,4,8,9,13 --> the probability is 1/10

Again, for the set -13,-4,-3,-2,-1,1,2,3,4,13 --> the probability is 0. Insufficient.

Re: One number, n, is selected at random from a set of 10 intege [#permalink]
11 Jul 2014, 04:20

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.