probability of firemen, using proportions.

according to the newspaper approximately three-fourths of all firemen has decreased by 10% over the past two decades. Suppose 30 firemen are selected at random.

must find the probability that exactly 22 of the firemen are volunteers.

and then must find the probability that more than 25 of the firemen are volunteers.

and suppose 17 of the firemen are volunteers. is there any evidence to suggest that the proportion of the volunteer firemen has decreased?

finally, suppose 50 of the firemen are selected at random from one area, and then 50 are selected from another area, the is the probability that at least 40 of the firemen in each group will be volunteers?

i'm not sure how to set up these examples, i tried applying them and i couldn't get them right. please help.