Question 5080
 I think youu have to use Poisson distribution
 the mean (avg) of one bank failing is 1 for every 6 days.
 Hence, the mean is 5 =30/6 banks failing for 30 days .
 Now lambda = 5,
 Let the random variable of Poisson dist. with mean u = 5 (in 30 days).
 
 We have Pr(X=k) = u^k/k! *e^(-u)

 Hence, Pr(X =>1) = 1- Pr(X =0) = 1 - e^(-5) = 0.993

 Kenny