Probability Example

Two dice are thrown, what is the probability of getting the sum being 8 or the sum being 10?

Solution:

Number of sample points in throwing two dice at a time is n(S)=36 Let A= {the sum being 8}

\      A= {(6,2), (5,3) , (4,4), (3,5) , (2,6)}; P(A) =  5/36

B = {the sum being 10}

\     B = {(6,4), (5,5) (4,6)} ;                        P(B) =  3/36

A Ç B = { } ;  n(A Ç B) = 0

\     The two events are mutually exclusive

\     P(A È B) = P(A) + P(B)

5      3

=      --- + ---          

36    36

8      2

=   ----- = --

36     9