Back to photostream

Conditional Probability for GrAdE XII

Conditional Probability for GrAdE XIIThe probability of an event occurring when another event has already occurred is known as conditional probability.

 

The probability that event B occurs, given that event A has already occurred is

 

P(B|A) = P(A and B) / P(A).

This formula is derived from the general multiplication principle and algebra.

 

Since, we know that event A has occurred, we conclude that the sample space has reduced. The sample space S, is reduced to a sample space of A since we know A has taken place. The number in the event divided by the number in the sample space continues. The value of both A and B should be in A since A has already taken place and divided by the number in A. Dividing numerator and denominator of the right hand side by the number in the sample space S, we have the probability of A and B divided by the probability of A.

300 views
0 faves
0 comments
Uploaded on December 13, 2011
Taken on December 13, 2011