Answer: a)
Step-by-step explanation:
Given : For safety reasons, four different alarm systems were installed in the vault containing the safety deposit boxes at a Beverly Hills bank.
Each of the four systems detects theft with a probability of .99 independently of the others .
Probability for independent events occurs together =
.
Then, the probability that when a theft occurs, all four systems will detect it
= (0.99) x (0.99) x (0.99) x (0.99)
Hence, the probability that when a theft occurs, all four systems will detect it is .
Hence, the correct answer is a) .