6 A shopkeeper sells electric fans. The demand for fans follows a Poisson distribution with mean 3.2 per week.
- Find the probability that the demand is exactly 2 fans in any one week.
- The shopkeeper has 4 fans in his shop at the beginning of a week. Find the probability that this will not be enough to satisfy the demand for fans in that week.
- Given instead that he has \(n\) fans in his shop at the beginning of a week, find, by trial and error, the least value of \(n\) for which the probability of his not being able to satisfy the demand for fans in that week is less than 0.05 .