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:

Properties of Mean, Standard Deviation [#permalink]
08 Apr 2014, 07:10

1

This post was BOOKMARKED

Hi Guys,

Have my gmat in less than 36 hours and would appreciate help on the following:

Standard Deviation and Mean for a set of numbers

How does each change if: a. a certain number is added to all the numbers b. a certain number is subtracted from all the numbers c. a certain number is multiplied with all the numbers d. all the numbers are divided by a certain number

Re: Properties of Mean, Standard Deviation [#permalink]
08 Apr 2014, 08:14

2

This post received KUDOS

Expert's post

brobeedle wrote:

Hi Guys,

Have my gmat in less than 36 hours and would appreciate help on the following:

Standard Deviation and Mean for a set of numbers

How does each change if: a. a certain number is added to all the numbers b. a certain number is subtracted from all the numbers c. a certain number is multiplied with all the numbers d. all the numbers are divided by a certain number

If we add or subtract a constant to each term in a set: Mean will increase or decrease by the same constant. SD will not change.

If we increase or decrease each term in a set by the same percent (multiply all terms by the constant): Mean will increase or decrease by the same percent. SD will increase or decrease by the same percent.

Re: Properties of Mean, Standard Deviation [#permalink]
08 Apr 2014, 23:27

Thanks Bunuel, so am I right to say that if all the terms are divided by the same constant, the effect is not linear - i.e., cannot be determined unless we calculate the st.dev of the new set as well?

Re: Properties of Mean, Standard Deviation [#permalink]
09 Apr 2014, 01:16

Expert's post

brobeedle wrote:

Thanks Bunuel, so am I right to say that if all the terms are divided by the same constant, the effect is not linear - i.e., cannot be determined unless we calculate the st.dev of the new set as well?

No.

Multiplying is the same as dividing: for example, dividing by 2 is the same as multiplying by 1/2.

If we increase or decrease each term in a set by the same percent (multiply all terms by the constant): Mean will increase or decrease by the same percent. SD will increase or decrease by the same percent.

Type of Visa: You will be applying for a Non-Immigrant F-1 (Student) US Visa. Applying for a Visa: Create an account on: https://cgifederal.secure.force.com/?language=Englishcountry=India Complete...