Discrete and Continuous Random Variables.
1. 10% of undergraduate students carry credit card balances greater than $7000 (Reader's Digest, July 2002). Suppose 12 undergraduate students are selected randomly to be interviewed about credit card usage. What is the probability that at least 1 carries a balance greater than $7000?
2. Suppose that stock prices in the S&P500 can be approximately modeled as normal with mean $33.75 and standard deviation $10.80. If 20 of these stocks are selected at random, how many are expected to exceed $40.50?
3. What is the 3rd quartile for these stock prices?