Answer:
0.999987
Step-by-step explanation:
Given that
The user is a legitimate one = E₁
The user is a fraudulent one = E₂
The same user originates calls from two metropolitan areas = A
Use Bay's Theorem to solve the problem
P(E₁) = 0.0131% = 0.000131
P(E₂) = 1 - P(E₁) = 0.999869
P(A/E₁) = 3% = 0.03
P(A/E₂) = 30% = 0.3
Given a randomly chosen user originates calls from two or more metropolitan, The probability that the user is fraudulent user is :
= 0.999986898 ≈ 0.999987