Answer:
a)
b)
Step-by-step explanation:
Conditional probability is the probability of one event occurring with some relationship to one or more other events.
The total probability rule (or the Law of Total Probability) breaks up probability calculations into distinct parts. P(AUB)=P(A)+P(B)-P(A and B)
The general multiplication rule formula is: P(A ∩ B) = P(A) P(B|A)=P(B)P(A|B)
We have the following probabilities:
Part a
We can use this multiplication rule:
For this part we want this probability:
And if we replace we got:
Part b
For this part we want the probability of one event in last year OR one event on the current year, so we can use the probability addition of events:
And for our case we have: