Answer:
a) P=0.0175
b) P=0.0189
Step-by-step explanation:
For both options we have to take into account that not only the chance of a "superevent" will disable both suppliers.
The other situation that will disable both is that both suppliers have their "unique-event" at the same time.
As they are, by definition, two independent events, we can calculate the probability of having both events at the same time as the product of both individual probabilities.
a) Then, the probability that both suppliers will be disrupted using option 1 is
b) The probability that both suppliers will be disrupted using option 2:
Pue = probability of a unique event
Pse = probability of a superevent