Need help with working this problem out with the right solution.

The following probability model describes the number of snow storms for Washington, D.C. for a given year:

Number of Storms Probability

0 .25

1 .33

2 .24

3 .11

4 .04

5 .02

6 .01

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?