A geologist has collected 22 specimens of basaltic rock and and 18 specimens of granite. The geologist instructs a laboratory assistant to randomly select 9 of the specimens for analysis.

(a) What is the probability that at least 4 of the selected specimens are granite?
(b) What is the expected number of granite specimens in the sample?
(c) If this same process is repeated every day, how many days (on average) will it take before getting a sample consisting entirely of granite?