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: The scores on a certain history test are shown above. How [#permalink]
10 Apr 2013, 01:40

Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?[/quote]

In this problem , yes you can calculate it in 10 seconds , if you can observe the total number of terms is 10. so since every number is a multiple of 10 you can do it easily .

Re: The scores on a certain history test are shown above. How [#permalink]
10 Apr 2013, 01:46

venkat18290 wrote:

Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?

In this problem , yes you can calculate it in 10 seconds , if you can observe the total number of terms is 10. so since every number is a multiple of 10 you can do it easily .

If there is a general method do let me know.[/quote]

Re: The scores on a certain history test are shown above. How [#permalink]
11 Apr 2013, 07:03

3

This post received KUDOS

Expert's post

score780 wrote:

Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?

40, 45, 45, 50, 50, 60, 70, 75, 95, 100

You can use deviations to find the mean here.

Assume that the mean is 60 since it's kind of in the middle.

Now notice that 50 is 10 less than 60 and 70 is 10 more so ignore both. Now 40, 45, 45, 50 together are 60 away from 60 while 75, 95, 100 are 90 away from 60.

So we have a total of 90 - 60 = 30 deviation from 60. Since there are 10 numbers, the average must be 30/10 = 3 more than 60 i.e it must be 63.

Re: The scores on a certain history test are shown above. How [#permalink]
06 Feb 2015, 01:34

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. _________________

Re: The scores on a certain history test are shown above. How [#permalink]
09 Feb 2015, 00:10

Expert's post

VeritasPrepKarishma wrote:

score780 wrote:

Thanks, yes this is the classic way. Is there a shortcut especially for calculating the mean without having to really do it?

40, 45, 45, 50, 50, 60, 70, 75, 95, 100

You can use deviations to find the mean here.

Assume that the mean is 60 since it's kind of in the middle.

Now notice that 50 is 10 less than 60 and 70 is 10 more so ignore both. Now 40, 45, 45, 50 together are 60 away from 60 while 75, 95, 100 are 90 away from 60.

So we have a total of 90 - 60 = 30 deviation from 60. Since there are 10 numbers, the average must be 30/10 = 3 more than 60 i.e it must be 63.

why did you not consider the second 50 in your calculation? Because then 40,45,45,50,50 would be 70 away from 60.

There is a second 50 which is 10 away from 60 and then there is a 70 which is also 10 away from 60. So together, they cancel off each other and give an average of 60 only. Or consider that the numbers on the left are 70 away but then the numbers on the right are 100 away since there is a 70 also which we haven't considered. Hence, overall, we still have 30 extra which will be distributed evenly among the 10 numbers. So the average will be 63. _________________

On September 6, 2015, I started my MBA journey at London Business School. I took some pictures on my way from the airport to school, and uploaded them on...

When I was growing up, I read a story about a piccolo player. A master orchestra conductor came to town and he decided to practice with the largest orchestra...

Amy Cuddy, Harvard Business School professor, at TED Not all leadership looks the same; there is no prescribed formula for what makes a good leader. Rudi Gassner believed that...

We are thrilled to welcome the Class of 2017 to campus today, and data from the incoming class of students indicates that Kellogg’s community is about to reach a...