Because of a mistake in packaging, a case of 11 bottles of wine contained 6 of brand A and 5 of brand B, each without labels. All the bottles look alike and have an equal probability of being chosen. Four bottles are randomly selected. (Round to four decimal places)

(a) What is the probability that all four are brand A?

(b) What is the probability that exactly three are brand A?

(c) What is the probability that none is brand A?