If E and F denote the events
'the card drawn is a spade' and 'the card drawn is an ace' respectively, then
P(E) = 13
1
4
1
and P(F)
52
4
52
13
 
 
 
Also E and F is the event ' the card drawn is the ace of spades' so that
P(E ∩F) = 1
52
Hence
P(E|F) =
1
P(E
F)
1
152
P(F)
4
13
 
 
 
Since P(E) = 1
4 = P (E|F), we can say that the occurrence of event F has not
affected the probability of occurrence of the event E We also have
P(F|E) =
1
P(E
F)
1
52
P(F)
1
P(E)
13
4
 
 
 
 
Again,  P(F) = 1
13  = P(F|E) shows that occurrence of event E has not affected
the probability of occurrence of the event F Thus, E and F are two events such that the probability of occurrence of one of
them is not affected by occurrence of the other Such events are called independent events