Math Is Fun Forum

finitehelp

Member

Registered: 2009-06-21

Posts: 80

Probability test need help fast!

1. Given the three majors listed below, what is the probability of randomly selecting one person majoring in either Finance or Economics or Statistics:
Majors Number of People
Finance 6
Economics 5
Statistics 8
Finance and Economics 0
Finance and Statistics 3
Economics and Statistics 2
Fin and Econ and Stat 0

2. iven the data below on gender and college major:

Econ Stat Finance
Male 5 7 13
Female 15 13 12

What is the conditional probability of being a male, given that your major is economics or P(M|E):

3. You have just completed a dry cycle of your favorite t-shirts. Your dryer contains the
Following: 5 red
3 blue
2 pink
Assuming sampling with replacement, what is the probability of randomly selecting one red, one blue, and one pink in three random draws:

4.You have just completed a dry cycle of your favorite t-shirts. Your dryer contains the
Following: 5 red
3 blue
2 pink
Assuming sampling without replacement, what is the probability of randomly selecting one red, one blue, and one pink in three random draws:

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Probability test need help fast!

Hi finitehelp;

For 3) there are 3 ways:

Use the Multinomial distribution ( best way)

http://en.wikipedia.org/wiki/Multinomial_distribution

Second way:

There are six ways to arrange r , b , p  each one of them
has a probability of (5 * 3 * 2) / ( 10 * 10 *10)

Third way: Ordinary generating function:

Look at the coefficient of the bpr term which is 9 / 50 or .18 Notice how this method has solved for the entire sample space.

4) the answer is 1 / 4 and there are 2 ways to do this.

First way: Use the Multivariate hypergeometric distribution: (best way)

http://en.wikipedia.org/wiki/Hypergeome … stribution

Second way:

There are six ways to arrange r , b , p  each one of them
has a probability of (5 * 3 * 2) / ( 10 * 9 *8)

Last edited by bobbym (2009-09-23 12:28:00)

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