Question: The number of shares traded daily on the New York Stock Exchange (NYSE) is referred to as the volume of trading. During the first three months of 2006, daily volume ranged from 1.424 billion to 2.170 billion (NYSE Group, www.nyse.com, April 28, 2006). Assume that the number of shares traded on the NYSE is a normally distributed random variable, with a mean of 1.8 billion and a standard deviation of 0.15 billion. For a randomly selected day, what is the probability that the volume is
a. below 1.5 billion?
b. below 1.7 billion?
c. above 2.0 billion?
d. above 2.3 billion?