Answer: a) 0.05
b) 0.56
Step-by-step explanation:
Let A be denote the event that gas station purchase gasoline.
B be denote the event that gas station purchase oil.
As per given description, we have
P(A)-0.91 , P(B)= 0.09 , P(A ∩B)=0.05
Then, the probability that a driver purchases oil, given that he or she purchases gasoline will be :-
[tex]P(B|A)=\dfrac{P(A\cap B )}{P(A)}[/tex] [Conditional probability formula.]
[tex]P(B|A)=\dfrac{0.05}{0.91}=\dfrac{5}{91}\\\\=0.0549450549451\approx0.05[/tex]
Similarly , The probability that a driver purchases gasoline, given that he or she purchases oil will be :-
[tex]P(A|B)=\dfrac{P(A\cap B )}{P(B)}[/tex]
[tex]P(A|B)=\dfrac{0.05}{0.09}=\dfrac{5}{9}\\\\=0.555555555556\approx0.56[/tex]