Respuesta :
Answer:
0.1739 = 17.39% probability that the cab actually was blue
Step-by-step explanation:
Conditional Probability
We use the conditional probability formula to solve this question. It is
[tex]P(B|A) = \frac{P(A \cap B)}{P(A)}[/tex]
In which
P(B|A) is the probability of event B happening, given that A happened.
[tex]P(A \cap B)[/tex] is the probability of both A and B happening.
P(A) is the probability of A happening.
In this question:
Event A: Witness asserts the cab is blue.
Event B: The cab is blue.
Probability of a witness assessing that a cab is blue.
20% of 95%(yellow cab, witness assesses it is blue).
80% of 5%(blue cab, witness assesses it is blue). So
[tex]P(A) = 0.2*0.95 + 0.8*0.05 = 0.23[/tex]
Probability of being blue and the witness assessing that it is blue.
80% of 5%. So
[tex]P(A \cap B) = 0.8*0.05 = 0.04[/tex]
What is the probability that the cab actually was blue?
[tex]P(B|A) = \frac{P(A \cap B)}{P(A)} = \frac{0.04}{0.23} = 0.1739[/tex]
0.1739 = 17.39% probability that the cab actually was blue
