(New page: Category:MA375Spring2009Walther I stole this from the XKCD rss feed, but figured it apropos enough to share with the group. Here it is! -Mark Sue and Bob take turns rolling a 6-sid...)
 
Line 12: Line 12:
  
 
The answer is '''not''' 5/36.
 
The answer is '''not''' 5/36.
 +
 +
----
 +
 +
[[Riddle 2 Solution]]

Revision as of 09:17, 12 February 2009


I stole this from the XKCD rss feed, but figured it apropos enough to share with the group. Here it is!

-Mark

Sue and Bob take turns rolling a 6-sided die. Once either person rolls a 6, the game is over. Sue rolls first. If she doesn’t roll a 6, Bob rolls the die; if he doesn’t roll a 6, Sue rolls again. They continue taking turns until one of them rolls a 6.

Bob rolls a 6 before Sue.

What is the probability Bob rolled the 6 on his second turn?

The answer is not 5/36.


Riddle 2 Solution

Alumni Liaison

Correspondence Chess Grandmaster and Purdue Alumni

Prof. Dan Fleetwood