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: 20 throws of a die produces following results score ==> # [#permalink]
09 Aug 2012, 06:33

Bunuel, Why are we assuming that the die is fair? Probability of a number greater than 3.5, in above example, = {# of occurrences of 4,5 and 6}/Total number of throws.

Re: 20 throws of a die produces following results score ==> # [#permalink]
09 Aug 2012, 07:21

1

This post received KUDOS

Expert's post

voodoochild wrote:

Bunuel, Why are we assuming that the die is fair? Probability of a number greater than 3.5, in above example, = {# of occurrences of 4,5 and 6}/Total number of throws.

= 8/20 Correct? Please let me know your thoughts.

Thanks

We can assume that the die is fair, because if we don't (so if we don't know that the probability of each face is 1/6), then we won't be able to solve this question at all. You cannot extrapolate the results of 20 throws to get the probability of each face if the die is unfair.

20 throws of a die produces following results

SCORE -- NUMBER OF OCCURRENCES ---1-------------------4 ---2-------------------3 ---3-------------------5 ---4-------------------2 ---5-------------------2 ---6-------------------4

What is the probability that one more throw to this series will increase the mean score?

A. 1/6 B. 1/3 C. 1/2 D. 2/3 E. 5/6

The average score now is \frac{total \ score}{# \ of \ throws}=\frac{1*4+2*3+3*5+4*2+5*2+6*4}{20}=\frac{67}{20}=3.something.

Now, the average score will increase if we get more than the current average, so if we get 4, 5, or 6 on the next throw. The probability of that is 3/6=1/2.

Re: 20 throws of a die produces following results [#permalink]
09 Aug 2012, 07:40

Ok. But here's a question from the GMATPrep. The question doesn't assume that the random variable X's values are equally likely. Can you please explain why is that? The calculation steps are very similar. In official problem, we just have to compute the range of valid values for 'x'.

Re: 20 throws of a die produces following results [#permalink]
09 Aug 2012, 07:57

Expert's post

voodoochild wrote:

Ok. But here's a question from the GMATPrep. The question doesn't assume that the random variable X's values are equally likely. Can you please explain why is that? The calculation steps are very similar. In official problem, we just have to compute the range of valid values for 'x'.

Thanks

This question is very different from the previous one. We have that a certain experiment produced the following results:

{1, 1, 1, 2, 3, 3, 3, 4, 5, 5, 5, 6, 7, 7, 7}. Total of 15 results.

We are asked to find the probability that |x-4|>1.5, where x is randomly chosen number from the above set. Now, in order the give inequality to hold true we must choose 1, 2, 6, or 7 (or anything but 3, 4, or 5). The probability of that is 8/15.

Re: 20 throws of a die produces following results [#permalink]
01 Oct 2014, 02:22

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. _________________

Great to know you are joining Kellogg. A lot was being talked about your last minute interview on Pagalguy (all good though). It was kinda surprise that you got the...

This is a long overdue post! A lot of Indian applicants, having scheduled interviews in March, reached out to me asking about my interview experience with Kellogg. I had a...