Answer:
13.53% probability that no earthquakes with a magnitude of 6.5 or greater strike the San Francisco Bay Area in the next 40 years
Step-by-step explanation:
In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:

In which
x is the number of sucesses
is the Euler number
is the mean in the given time interval.
According to geologists, the San Francisco Bay Area experiences five earthquakes with a magnitude of 6.5 or greater every 100 years.
One earthquake each 100/5 = 20 years.
What is the probability that no earthquakes with a magnitude of 6.5 or greater strike the San Francisco Bay Area in the next 40 years?
40 years, so 
This probability is P(X = 0).


13.53% probability that no earthquakes with a magnitude of 6.5 or greater strike the San Francisco Bay Area in the next 40 years