A mom brings her child every day a chocolate with a toy inside, the toy is random. The boy is happy when he gets a car as a toy. His mom decided to look in which supermarket the probability of getting a car is the highest.
The mom has come to the following result: Supermarket A:$0.2$ ,Supermarket B:$0.3$, Supermarket C:$0.1$, Supermarket D: $0.05$.
The mom doesn't always buy the chocolate at the same supermarket. The frequency of visiting the exact supermarket is: Supermarket A:$0.2$ ,Supermarket B:$0.4$, Supermarket C:$0.25$, Supermarket D: $0.15$.
- How high is the probability that the boy gets a car in his chocolate?
- He found a car in his chocolate. How high is the probability that his mother bought the chocolate at supermarket C?
I am pretty lost here. Do not know even where to start. My assumption is that this has something to do with conditional probability, but I cannot see how to divide this is in events.
Law of total probability: $$ P(car)=P(car|A)P(A)+P(car|B)P(B)+P(car|C)P(C)+P(car|D)P(D) $$ Then Bayes rule: $$ P(C|car)=\frac{P(car|C)P(C)}{P(car)} $$