Please help.

Question: According to NOAA s report. a major flooding in Boston in a given year has a Poisson distribution with a mean occurrence of 2.5. 1. What is the probability that there will be at least one major flooding in the next one year? 2. Using the same parameter in a), what is the probability that it will be at least 6 months until the next major flooding? 3. If one year has passed with no flooding. what is the probability that there will be flooding within the next six months