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 350,000 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:

If x is an integer, how many even numbers does set (0, x , [#permalink]
22 Nov 2007, 05:03

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

100% (04:29) correct
0% (00:00) wrong based on 2 sessions

If x is an integer, how many even numbers does set (0, x , x^2, ..., x^9) contain?

1) The mean of the set is even
2) The standard deviation of the set is 0

Can someone explain to me how we can determine whether the sum of the series is odd or even by looking at Statement 1? For example, does x have to be odd for 0 + x + x^2 + ...+ x^9 to be odd? Why? Thanks.

Re: DS: Even numbers [#permalink]
22 Nov 2007, 06:14

GK_Gmat wrote:

If x is an integer, how many even numbers does set (0, x , x^2, ..., x^9) contain?

1) The mean of the set is even 2) The standard deviation of the set is 0

Can someone explain to me how we can determine whether the sum of the series is odd or even by looking at Statement 1? For example, does x have to be odd for 0 + x + x^2 + ...+ x^9 to be odd? Why? Thanks.

Im sure I am wrong - but if the SD is 0 - doesn't that mean all the numbers are the same? So if 0 is included, x = 0

Edit - I see A as being suff now... D

Last edited by alrussell on 22 Nov 2007, 06:26, edited 1 time in total.

Re: DS: Even numbers [#permalink]
22 Nov 2007, 11:30

GK_Gmat wrote:

If x is an integer, how many even numbers does set (0, x , x^2, ..., x^9) contain?

1) The mean of the set is even 2) The standard deviation of the set is 0

Can someone explain to me how we can determine whether the sum of the series is odd or even by looking at Statement 1? For example, does x have to be odd for 0 + x + x^2 + ...+ x^9 to be odd? Why? Thanks.

if the mean is even, then definitely the sum is also even because even divided by odd or even only be even. only # of elements can be even or odd.

also got D.

1: since there are 10 elements (and out of 10, 9 are power of x), the sum of x and its powers should be even. if x is odd, the sum of x and its powers cannot be even. so x must be even and eventually all are even.

2: SD 0 means all are zero because the set has 0 as an element. when a set has 0 as an element and its SD is 0, then all elements must be 0. so all elements are even.

D.

gmatclubot

Re: DS: Even numbers
[#permalink]
22 Nov 2007, 11:30

safe.txmblr Can business make a difference in the great problems that we face? My own view is nuanced. I think business potentially has a significant role to play...

safe.txmblr Rebecca Henderson on the viability of the purpose-driven firm: We don’t want business people making policy...but on the other hand, what can business people do to...