3) Sun Microsystems has approximately 50% of the high-end Unix machines market with its closest competitor being IBM. Suppose that 15 firms were in the market to purchase a high-end Unix machine. Assume that these firms listened to sales pitches by all the major players selling high-end Unix machines.
a) What are the mean and the standard deviation of the number of firms that purchase a Unix machine from Sun Microsystems?
b) What is the probability that exactly 8 firms purchase a Unix machine from Sun Microsystems?
c) What is the probability that between 5 and 10 firms, inclusively, purchase a Unix machine from Sun Microsystems?