The number of cases of tetanus reported in the U.S. during a single month in 1989 has a poisson distribution with a parameter of lambda= 4.5. 1. What is the probability that exactly one case of tetanus will be reported during a given month? 2. What is the probability that at most two cases of tetanus will be reported? 3. What is the porbability that four or more cases will be reported. 4. What is the mean number of cases of tetanus reported in a one month period? What is the standard deviation?