It is reported that 25% of American households use a cell phone exclusively for their telephone service. In a sample of twelve households, find the probability that

a) Find the probability that no household uses a cell phone as their exclusive telephone service. (Round your answer to 4 decimal places.)

b) Exactly 6 households exclusively use a cell phone for telephone service. (Round your answer to 4 decimal places.)

c) Find the mean number of households exclusively using cell phones. (Round your answer to 2 decimal places.)