Posted by 5GJW on March 21, 1999 at 11:32:05 {MWZNJSg.uPfFk}:
In Reply to: *****Evolutionism and Creationism posted by J.H. on March 21, 1999 at 04:44:12:
This is the definition of probability, applied to this question. As it is the definition, there is no proof, we simply said that this is what it means.
Given:
There is a set of 100 people.
All are either JW or Catholic(J or
C)
There is at least one J and at least one C.
In any 2 samples of the set, the probability of at least 1*C is equal to 1 ( P(C) = 1).
This can be rephrased as the probability of 2*J = 0 (P(2J)=0)
These events are not mutually exclusive, the first selection changes the probability of the second selection.
If we select one element from the set, the probability of selecting a J = (Number of Js in Set)/(Size of set).
The probability of 2*J can be expressed as P(2J) = ((Number of Js)/(100)) * (Number of Js - 1)/(99)).
In order for P(2J) = zero to be true, Number of Js = 0 or 1. As it is given that there is at least 1 J, 1 is the correct answer.
5GJW, with textbook in hand