Posted by SAM on .
Yesterday, at a local restaurant, 60% of the customers ordered a burger.
If 42% of the customers ordered a burger and fries, what is the probability that a customer who ordered a burger also ordered fries?
If 15% of the customers ordered a burger and onion rings, what is the probability that a customer ordered onion rings given that he/she ordered a burger?

MATH! :( Conditional Probability 
MathMate,
The conditional probability of event A happening given B is given by
P(AB) = P(A∩B)/P(B)
In the example,
B=customers ordered burgers
P(B)=0.60
F=customers ordered Fries
P(B∩F)=0.42
So probability of ordering fries given the customer ordered a burger is
P(FB)=P(B∩F)/P(B)=0.42/0.6=0.7
and similarly
R=customers ordered onion Rings
P(B∩R)=0.15
What is
P(RB)?