Answer:
0.002991
Step-by-step explanation:
Let
User is legitimate one = E₁
User is fraudulent one = E₂
User originates calls from two metropolitan = A
Therefore, according to the question
P(E₁) = 1 - 0.01% = 1 - 0.0001 = 0.9999
P(E₂) = 0.0001
P(A/E₁) = 1% = 0.01
P(A/E₂) = 30% = 0.30
Now,
P(E₂/A) = [tex]\frac{P(E_2)\timesP(A/E_1)}{P(E_1)\timesP(A/E_1)+P(E_2)\timesP(A/E_2)}[/tex]
or
P(E₂/A) = [tex]\frac{0.9999\times0.01}{0.0001\times0.01+0.0001\times0.3}[/tex]
or
P(E₂/A) = 0.002991