The Following Probability Model Describes the Number of Snowstorms for Washington

Short Answer

The following probability model describes the number of snowstorms for Washington, D.C. for a given year: The probability of 7 or more snowstorms in a year is 0.
a. What is the probability of more than 2 but less than 5 snowstorms?
b. Given this a particularly cold year (in which 2 snowstorms have already been observed), what is the conditional probability that 4 or more snowstorms will be observed?
c. If at the beginning of winter there is a snowfall, what is the probability of at least one more snowstorm before winter is over?