If we define a random variable to have two possible outcomes, the monthly rainfall in June, July, or August to be less than 1 in. and the monthly rainfall to be 1 in. or greater, use the data of Table 2-8 to estimate the probabilities of the two events. Find the following probabilities:
(a) Exactly 2 months in the months of June, July, or August in the next 5 years will have less than 1 in. of rainfall; (b) in the next 2 years, there will be no monthly rainfall during June, July, or August that is less than 1 in.; (c) in any one year, all monthly rainfalls during June, July, and August are less than 1 in.; (d) in any 7-yr period, there will be no more than two months in June, July, and August where the rainfall is less than 1 in.
From Mc Cuen, Hydrologic Analysis