The number of rescue calls received by the rescue squad in city follows Poisson distribution with mu = 2.83 per day. The squad can manage at most four calls day.

1. Find out the probability that the squad will be capable to handle all calls on a specific day?
2. The squad wish to have at least 95% confidence of being capable to manage all the calls received in the day. At least how many calls a day must the squad be prepared for?
3. Supposing that the squad can manage at most four calls a day, find out the largest value of f.1 that would yield 95% confidence that the squad can handle manage all calls?