View Single Post
  #2  
Old 08-29-2007, 04:50 PM
BruceZ BruceZ is offline
Senior Member
 
Join Date: Sep 2002
Posts: 4,078
Default Re: my friend says he\'s unlucky

[ QUOTE ]
Series 1: 25 cards in a deck. 14 unfavorable cards. I hold 14 cards. The probability that 12 out of the 14 are unfavorable.

[/ QUOTE ]

C(14,12)*C(11,2) / C(25,14) =~ 0.11% or 1 in 891


[ QUOTE ]
Series 2: given 150 people, 28 seats available, the probability of NOT getting a seat 15 times in a row. Is this just 1/150 + 1/149 + ... 1/135?

[/ QUOTE ]

No. (122/150)^15 =~ 4.5% or 1 in 22
Reply With Quote