bank failure once every six years, on average, probability of at least one bank failure in the next 30 years

Question

in a certain country there is a bank failure once every six years, on average. What is the probability of at least one bank failure in the next 30

Answer 1

current failure rate = 1F/6year

time period = 30 years

expected failure  = 1/6 = X/30

thus, X = 30/6 = 5

 

so the chances are 5 to 1 that there will be at least 1 failure within 30 years