Respuesta :
Answer:
Answer 1: Given that the case from this three-year period was not appealed, the probability that the judge was not Judge Brown is 0.689.
Answer 2: Probability that exactly 3 of the 4 accounts have values of at least $1000 is 0.2068.
Step-by-step explanation:
Answer 1:
Probabilities that each of the judges saw the cases are:
P(Judge Adams) = 0.27
P(Judge Brown) = 0.31
P(Judge Carter) = 1 - (0.27+ 0.31)
P(Judge Carter) = 0.42
Probabilities that the cases of each of the judges were appealed(A) can be represented as a conditional probability:
P(A | Judge Adams) = 0.05
P(A | Judge Brown) = 0.07
P(A | Judge Carter) = 0.09
Hence we can find the probabilities that the cases of each of the judges were not appealed:
P(Not A | Judge Adams) = 1 - 0.05 = 0.95
P(Not A | Judge Brown) = 1 - 0.07 = 0.93
P(Not A | Judge Carter) = 1 - 0.09 = 0.91
We need to find the probability P(Judge Brown | Not A). For this we will use the Baye's Theorem:
P(Ai|B) = [P(Ai)P(B|Ai)]/[P(A1)P(B|A1) + P(A2)P(B|A2) + P(A3)P(B|A3)]
P(Judge Brown | Not A) = [P(Judge Brown)*P(Not A | Judge Brown)]/[P(Judge Adams)*P(Not A | Judge Adams) + P(Judge Brown)*P(Not A | Judge Brown) + P(Judge Carter)*P(Not A | Judge Carter)]
P(Judge Brown | Not A) = [0.31*0.93]/[(0.27*0.95) + (0.31*0.93) + (0.42*0.91)]
= 0.2883/(0.2565 + 0.2883 + 0.3822)
= 0.2883/0.927
P(Judge Brown | Not A) = 0.311
P(Not Judge Brown | Not A) = 1 - 0.311 = 0.689
Given a case from this three-year period was not appealed, the probability the judge in the case was not Judge Brown is 0.689
Answer 2:
We will use the binomial distribution formula to find out the probability that exactly 3 of the 4 accounts have values of at least $1000. The binomial distribution formula is:
P(X=x) = ⁿCₓ pˣ qⁿ⁻ˣ
Where n = no. of trials
x = no. of successful trials
p = probability of success
q = probability of failure = 1-p
We have,
n = 46
x = 4
p = (46-25)/46 = 21/46
q = 25/46
P(X=3) = ⁴C₃ (21/46)³ (25/46)⁴⁻³
= 4 * (21/46)³ (25/46)¹
P(X=3) = 0.2068