An appliance store sells20refrigerators each week. Ten percent of all purchasers of a refrigerator buy an extended warranty. LetXdenotes the number of the next20purchasers who do so.(20 marks)

a.Verify thatXsatisfies the conditions for a binomial random variable, and findnandp.(5 marks)

b.Find the probability thatXis zero.(2 marks)

c.Find the probability thatXis two, three, or four.(5 marks)

d.Find the probability thatXis at least five.(8 marks)