The mean number of days with 0.01 inch or more precipitation per month for Lewistown, Idaho, is about 8. Find the probability that in a given month…

The mean number of days with 0.01 inch or more precipitation per month for Lewistown, Idaho, is about 8.7. Find the probability that in a given month a) there are exactly 9 days with 0.01 inch or more precipitation, b) there are at most 9 days with 0.01 inch or more precipitation, and c) there are more than 9 days with 0.01 inch or more precipitation.