Volume of Apple Stock In 2007, Apple stock had a mean daily volume of 35.1 million shares, according to Yahoo! Finance. A random sample of 40 trading days in 2010 resulted in a sample mean of 23.6...

Volume of Apple Stock In 2007, Apple stock had a mean daily volume of 35.1 million shares, according to Yahoo! Finance. A random sample of 40 trading days in 2010 resulted in a sample mean of 23.6 million shares with a standard deviation of 11.7 million shares.

(a) Based on the histogram and boxplot shown (from Stat Crunch), why is a large sample necessary to conduct a hypothesis test about the mean?

(b) Does the evidence suggest that the volume of Apple stock has changed since 2007?