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Rumor Mill (Posted on 2004-12-03) Difficulty: 4 of 5
Waldo is having a party and has 50 guests, among whom is his brother Basil.

Basil starts a rumor about Waldo; a person hearing this rumor for the first time will then tell another person chosen uniformly at random the rumor, with the exceptions that no one will tell the rumor to Waldo or to the person they heard it from.

If a person who already knows the rumor hears it again, they will not tell it again.

What's the probability that everyone, except Waldo, will hear the rumor before it stops propagating?

What if each person told two people chosen uniformly at random?

No Solution Yet Submitted by SilverKnight    
Rating: 4.0000 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Stat. analysis of Charlie's part 2 | Comment 4 of 13 |

First off, I agree with your part 1 and have nothing to add to it.

I couldn't see how to do part two so I checked your simulation data.

A 95% confidence interval for your sample proportion is [.000362,.000442] 

Your solution(?) is different by a statistically significant margin (p=.000369 is the chance of your simulation being so far off if your solution is correct)  I suspect the simulation is good, but I only glanced at the program.

Sorry, I know that wasn't very relevant, but I got got done reviewing this stuff with my Stats class so its on my mind and I thought I'd share.


  Posted by Jer on 2004-12-03 18:41:21
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