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.
It appears that you are browsing the GMAT Club forum unregistered!
Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club
Registration gives you:
Tests
Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.
Applicant Stats
View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more
Books/Downloads
Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!
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:
I'm not going to go into "how to solve" since many others are do it much better than I do.
I think for this question the key factors to know are: 1) definition of standard definition 2) definition of "0"
remember, when all numbers are the same or if there is one number in the set, the standard deviation is 0. 0 is not a positive integer. (positive integer is > 0).
SD problems are the ones i miss and i failed here too.... _________________
Regards, Harsha
Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat
On a side note, when a question tells you a set S has numbers x,y,z - do we assume that x y z will always be different numbers? or can they be the same number, but repeated 3 times.
BELOW IS REVISED VERSION OF THIS QUESTION:
Each term of set T is a multiple of 5. Is standard deviation of T positive?
The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, a low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values. So, basically we can say that it in a sense measures the distance and the distance can not be negative, which means that the standard deviation of any set is greater than or equal to zero: .
Next, the standard deviation of a set is zero if and only the set consists of identical numbers (or which is the same if the set consists of only one number).
(1) Each term of set T is positive --> if T={5} then then SD=0 but if set T={5, 10} then SD>0. Not sufficient.
(2) Set T consists of one term --> any set with only one term has the standard deviation equal to zero. Sufficient.
I'm not going to go into "how to solve" since many others are do it much better than I do.
I think for this question the key factors to know are: 1) definition of standard definition 2) definition of "0"
remember, when all numbers are the same or if there is one number in the set, the standard deviation is 0. 0 is not a positive integer. (positive integer is > 0).
Sorry but is there some mistake here. Thought this helpful set of Bunuel
I'm not going to go into "how to solve" since many others are do it much better than I do.
I think for this question the key factors to know are: 1) definition of standard definition 2) definition of "0"
remember, when all numbers are the same or if there is one number in the set, the standard deviation is 0. 0 is not a positive integer. (positive integer is > 0).
Sorry but is there some mistake here. Thought this helpful set of Bunuel
I'm not going to go into "how to solve" since many others are do it much better than I do.
I think for this question the key factors to know are: 1) definition of standard definition 2) definition of "0"
remember, when all numbers are the same or if there is one number in the set, the standard deviation is 0. 0 is not a positive integer. (positive integer is > 0).
Sorry but is there some mistake here. Thought this helpful set of Bunuel
Although it's true that this problem is tests on the concept or definition of the standard deviation, I think that I'd like to further break up my the evaluation of the two statements. Using the concept, here is how I'd solve this:
Set T = {5 * I} where I = 1, 3, 5, 7, ..., or n Question: Is SD = positive? S1: All member of T are positive. Here are some of rules: If the set consists of only one item, then SD = 0 (because mean is same as the item). If the set consists of evenly distributed number, then SD > 0 So, making use of these two rule, we know that this answer is not sufficient.
S2: T consists of only one number. In this case, we know that SD is always 0. So, the answer to the question is always no. Therefore, S2 is sufficient.