1. Suppose that past history shows that 0.75 of Tsinghua students prefer Bread.

A sample of 10 students is to be selected.

Calculate:

a) the probability that exactly 4 students prefer bread.

b) the probability that at least 9 students prefer bread.

c) the probability that more than 6 students prefer bread

2.The average number of handphones sold by the Apple Bhd is three handphones per day.

a) What is the probability that exactly four hand phones will be sold tomorrow?

b) What is the probability that less than two handphones will be sold tomorrow?

General probability distribution: Mean or expected value u = E(X) = EX . P(X) Variance 0 = E ( X-/). P(X) Standard deviation o = Vo2 Binomial Distribution: Mean u = n. p Variance 62 = n .p. q Standard deviation = n. p. q X n-X Probability P(X) = "cr.p q for OSX Sn Poisson Distribution: var(x) = ProbabilityP (x) = - x ! for x = 0, 1, 2, 3 ... ... Normal Distribution Probability z =