A major hurricane is a hurricane with wind speeds of 111 miles per hour or greater. During the 20th century, the mean number of major hurricanes to strike the U.S. mainland per year was about 0.5. Find the probability that in a given year a) exactly one major hurricane will strike the U.S. mainland, b) at most one major hurricane will strike the U.S. mainland, and c) more than one major hurricane will strike the U.S. mainland.