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:

of the students at a certain school, 50% of the students are [#permalink]
15 Mar 2005, 07:15

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct
0% (00:00) wrong based on 0 sessions

of the students at a certain school, 50% of the students are in class a, 30% of the students are in class b, 20% of the students are in class c. of the students in class a, 20% are wearing eyeglasses. of the students in class b, 10% are wearing eyeglasses. of the students c, 10% are wearing eyeglasses. if a student is selected at random, what is the probability that the student is in class b ?

I think the question is not complete...because the glasses story is totally useless so I assume that normally it should be a question in realtion with the prob of someone from class b with glasses or without glasses...

christoph please explain or check again your question because I don't get it... please explain the way of thinking

possible outcomes: 30% of the students are in class b * of the students in class b, 10% are wearing eyeglasses = 0,1 * 0,3 = 0,03

all outcomes: 50% of the students are in class a * of the students in class a 20% are wearing eyeglasses + 30% of the students are in class b * of the students in class b, 10% are wearing eyeglasses + 20% of the students are in class c * of the students c, 10% are wearing eyeglasses = 0,15

Re: PS - Bayes Theorem [#permalink]
21 Mar 2005, 02:56

christoph wrote:

if a student is selected at random, what is the probability that the student is in class b ?

I think there is a mistake in the first post. Actually the answer to this question should be :
total outcome : all students
favorable outcome : all students in class b

however, the solution you've given us is
total outcome : all students with glasses
favorable outcome : all students with glasses in class b

The question asks "what is the probability that the student is in class b": How can the possible outcomes depend on the number of students wearing glasses or not?

Is there something missing in the question or something which I have misinterpreted?

For my Cambridge essay I have to write down by short and long term career objectives as a part of the personal statement. Easy enough I said, done it...