Quick Question

[Matty]

This has immediate real-world implications for me, so please don't steer me wrong.

I have little interest in, or knowledge of probability, so if this is ridiculously simple please excuse.

A person is allowed to pull 4 balls out of a sack of ten without looking into the bag. He will then throw away one and only one red ball (if he pulls one out) leaving him with three balls.

Assume there are 7 black balls and 3 red balls in the sack. What are the chances that the person will end up with at least one red ball (after throwing away one). So basically, what are his chance of pulling 2 or more red balls out of the sack?

Then assume there are 6 black and 4 red in the sack.

8 black and 2 red.

Thanks.

[Matty]

You all have 7 hours.

[BruceZ]

[ QUOTE ]
This has immediate real-world implications for me, so please don't steer me wrong.

I have little interest in, or knowledge of probability, so if this is ridiculously simple please excuse.

A person is allowed to pull 4 balls out of a sack of ten without looking into the bag. He will then throw away one and only one red ball (if he pulls one out) leaving him with three balls.

Assume there are 7 black balls and 3 red balls in the sack. What are the chances that the person will end up with at least one red ball (after throwing away one). So basically, what are his chance of pulling 2 or more red balls out of the sack?

[/ QUOTE ]

[C(3,2)*C(7,2) + C(3,3)*C(7,1)] / C(10,4) = 1/3


[ QUOTE ]
Then assume there are 6 black and 4 red in the sack.

[/ QUOTE ]

[C(4,2)*C(6,2) + C(4,3)*C(6,1) + C(4,4)] / C(10,4) =~ 54.76%


[ QUOTE ]
8 black and 2 red.

[/ QUOTE ]

C(2,2)*C(8,2)/C(10,4) = 1/7.5 =~ 13.33%

[hoopsie44]

How about blue balls? Are they a consideration?

[Matty]

Thank you.

[JaysonWeberFCP]

I just got out of College 2 weeks ago... this question reminded me of my Business Analysis Final... My head now hurts... Thanks for showing all your work BruceZ /images/graemlins/laugh.gif

[BruceZ]

[ QUOTE ]
I just got out of College 2 weeks ago... this question reminded me of my Business Analysis Final... My head now hurts... Thanks for showing all your work BruceZ /images/graemlins/laugh.gif

[/ QUOTE ]

I don't know if you're being sarcastic, but what I showed actually was all of my work.

[closer2313]

Bruce, I want to take this time to tell you that you are my hero.

That is all.

[Thythe]

[ QUOTE ]
[ QUOTE ]
I just got out of College 2 weeks ago... this question reminded me of my Business Analysis Final... My head now hurts... Thanks for showing all your work BruceZ /images/graemlins/laugh.gif

[/ QUOTE ]

I don't know if you're being sarcastic, but what I showed actually was all of my work.

[/ QUOTE ]

I don't think he was being sarcastic.