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:

Re: Set A {3,3,3,4,5,5,5} has a standard deviation of 1. [#permalink]
02 Sep 2012, 20:16

1

This post received KUDOS

Variance = (sum of (squares of difference of each number from mean )) / total number of numbers Standard deviation = sqrt Variance

When we multiply all the numbers by something then while calculating the standard deviation we can take out that thing common new standard deviation will be equal to value by which we multiplied all the number* old standard deviation.

Ex: Suppose we have 4 entries a,b,c,d and suppose the mean is m Then standard deviation = sqrt { { (a-m)^2 + (b-m)^2 + (c-m)^2 + (d-m)^2 } / 4 }

Now we multiply all the number by 4 so the new set will be 4a, 4b, 4c, 4d the new mean will be 4a + 4b+ 4c+ 4d /4 = 4 *( (a+b+c+d) /4 ) = 4m

Re: Set A {3,3,3,4,5,5,5} has a standard deviation of 1. [#permalink]
02 Sep 2012, 20:38

2

This post received KUDOS

Smita04 wrote:

Set A {3,3,3,4,5,5,5} has a standard deviation of 1. What will the standard deviation be if every number in the set is multiplied by 4?

A)1 B)2 C)4 D)8 E)16

Points to remember - 1. If one Add/Subtract the same amont from every term in a set, SD doesn't change. 2. If one Multiply/Divide every term by the same number in a set, SD changes by same number.

Hence the answer to the above question is C. Cheers! _________________

----------------------------------------------------------------------------------------- What you do TODAY is important because you're exchanging a day of your life for it! -----------------------------------------------------------------------------------------

Re: Set A {3,3,3,4,5,5,5} has a standard deviation of 1. [#permalink]
03 Oct 2014, 06:09

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. _________________

I´ve done an interview at Accepted.com quite a while ago and if any of you are interested, here is the link . I´m through my preparation of my second...

It has been a good week so far. After the disappointment with my GMAT score, I have started to study again, re-schedule the new test date and talked with...

It’s here. Internship season. The key is on searching and applying for the jobs that you feel confident working on, not doing something out of pressure. Rotman has...