The Educational Resource Service publishes information about wages and salaries in the public schools system in National Survey of Salaries and Wages in Public Schools. The mean annual salary of (public) classroom teachers is $49.0 thousand. A random sample of 90 classroom teachers in Hawaii yielded the annual salaries, in thousands of dollars, presented on the WeissStats CD. Use the technology of your choice to do the following.
a. Obtain a normal probability plot, boxplot, histogram, and stem-and-leaf diagram of the data.
b. Based on your results from part (a), can you reasonably apply the one-mean z-test to the data? Explain your reasoning.
c. At the 5% significance level, do the data provide sufficient evidence to conclude that the mean annual salary of classroom teachers in Hawaii is greater than the national mean? Assume that the standard deviation of annual salaries for all classroom teachers in Hawaii is $9.2 thousand.