Wednesday, June 9, 2010

How to estimate Probability with example

Introduction:

      Probability is an estimate of the likelihood of the occurrence of an event. An event is a set of possible outcomes resulting from a particular experiment. For example, estimate a possible event when a single six - sided numbered cube is rolled is {1, 4}. That is, the roll could be a 1 or a 4. In general, an event is any subset of a sample space (including the possibility of an empty set).

Estimate Probability – Examples

Example 1: Estimate the probability that an actor will get a film is ‘3/5’ and the probability that he will get on other film is 6/11. If the probability of getting at least one film is 5/7, what is the probability that he will get both the films?
Solution:
Here P(A) = 3/5, P(B) = 6/11
P(A or B)  =  5/7,  (P(A and B) = ?
By addition rule of probability:
P(A or B)  =  P(A) + P(B)  - P(A and B)
= 5/7  =  3/5 + 6/11  -  P(A and B)
or 5/7  =  63/55 – P(A and B)
or P(A and B)  =  63/55 – 5/7 = 166/385
P(A and B) =  166/385

Hope you like the above example. Please leave your comments, if you have any doubts.

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