The euro-zone crisis continues to wreak havoc on U.S. stock markets (The Wall Street Journal, June 8, 2012). A portfolio analyst wonders if the average trading volume on the Dow Jones Industrial Average (DJIA) has increased since the beginning of the year. She gathers data on daily trading volumes for a sample of 30 days. The data set, labeled DJIA_Volume, can be found on the text website.
a. She finds that the average trading volume in the beginning of the year was about 4,000 shares
(In millions). Specify the competing hypotheses to test her claim.
b. Specify the critical value(s) at the 5% significance level.
c. Compute the value of the test statistic.
d. At the 5% significance level, does it appear that trading volume has increased since the beginning of the year?