Security analysts are professionals who devote full-time efforts to evaluating the investment worth of a narrow list of stocks. The following variables are of interest to security analysts. Which are discrete and which are continuous random variables?
a. The closing price of a particular stock on the New York Stock Exchange
b. The number of shares of a particular stock that are traded each business day
c. The quarterly earnings of a particular firm
d. The percentage change in yearly earnings between 2011 and 2012 for a particular firm
e. The number of new products introduced per year by a firm
f. The time until a pharmaceutical company gains approval from the U.S. Food and Drug Administration to market a new drug