The Energy Information Administration reported that the mean retail price per gallon of regular-grade gasoline was $\$ 3.43$ (Energy Information Administration, July 2012). Suppose that the standard deviation was $\$ .10$ and that the retail price per gallon has a bell-shaped distribution.

a. What percentage of regular-grade gasoline sold for between $\$ 3.33$ and $\$ 3.53$ per gallon?

The Energy Information Administration of the U.S. Department of Energy provided time series data for the U.S. average price per gallon of conventional regular gasoline between January 2007 and March 2012 (Energy Information Administration website, April 2012). Use the Internet to obtain the average price per gallon of conventional regular gasoline since March 2012.

a. Extend the graph of the time series shown in Figure mentioned.

b. What interpretations can you make about the average price per gallon of conventional regular gasoline since March 2012?

c. Does the time series continue to show a summer increase in the average price per gallon? Explain.

The Energy Information Administration of the U.S. Department of Energy provided time series data for the U.S. average price per gallon of conventional regular gasoline between July 2006 and June 2009 (Energy Information Administration website, June 2009). Use the Internet to obtain the average price per gallon of conventional regular gasoline since June 2009. a. Extend the graph of the time series shown in Figure 1.1. b. What interpretations can you make about the average price per gallon of conventional regular gasoline since June 2009? c. Does the time series continue to show a summer increase in the average price per gallon? Explain.

The Energy Information Administration of the U.S. Department of Energy provided time series data for the U.S. average price per gallon of conventional regular gasoline between January 2007 and March 2012 (Energy Information Administration website, April 2012). Use the Internet to obtain the average price per gallon of conventional regular gasoline since March 2012.

a. Extend the graph of the time series shown before.

b. What interpretations can you make about the average price per gallon of conventional regular gasoline since March 2012?

c. Does the time series continue to show a summer increase in the average price per gallon? Explain.

The Energy Information Administration reported that the mean retail price per gallon of regular grade gasoline was 2.30 dollars (Energy Information Administration, February 27, 2006). Suppose that the standard deviation was 0.10 dollar and that the retail price per gallon has a bellshaped distribution.

$$\newline$$

What percentage of regular grade gasoline sold between 2.20 dollars and 2.40 dollar per gallon?

Using data available from the Energy Information Administration website, choose a few measures of U.S. or world energy consumption or production. Make comparisons that put these numbers in perspective.

The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the standard deviation is 1.2 hours and that the number of hours of sleep follows a bell-shaped distribution.

What is the z-value for an adult who sleeps 8 hours per night?

Choose the correct answer.

The U.S. Energy Information Administration predicts that the United States will become a net exporter of energy (a) sometime, (b) some time between 2020 and 2030.

The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the standard deviation is 1.2 hours and that the number of hours of sleep follows a bell-shaped distribution.

What is the z-value for an adult who sleeps 6 hours per night?

Every year, the U.S. Coast Guard collects data and compiles statistics on reported recreational boating accidents. These statistics are derived from accident reports that are filed by the owners/operators of recreational vessels involved in accidents. In 2009, 4730 recreational boating accident reports were filed. Figure mentioned provides a bar chart summarizing the number of accident reports that were filed each month (U.S. Coast Guard's Boating Safety Division website, August 2010).

a. Are the data categorical or quantitative?

b. Are the data time series or cross-sectional?

The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the standard deviation is 1.2 hours.

Use Chebyshev’s theorem to calculate the percentage of individuals who sleep between 4.5 and 9.3 hours.

Every year, the U.S. Coast Guard collects data and compiles statistics on reported recreational boating accidents. These statistics are derived from accident reports that are filed by the owners/operators of recreational vessels involved in accidents. In 2009, 4730 recreational boating accident reports were filed. Data given before provides a bar chart summarizing the number of accident reports that were filed each month (U.S. Coast Guard’s Boating Safety Division website, August 2010).

a. Are the data categorical or quantitative?

b. Are the data time series or cross-sectional?

c. In what month were the most accident reports filed? Approximately how many?

d. There were 61 accident reports filed in January and 76 accident reports filed in December. What percentage of the total number of accident reports for the year was filed in these two months? Does this seem reasonable?

e. Comment on the overall shape of the bar graph.

Every year, the U.S. Coast Guard collects data and compiles statistics on reported recreational boating accidents. These statistics are derived from accident reports that are filed by the owners/operators of recreational vessels involved in accidents. In 2009, 4730 recreational boating accident reports were filed. Figure 1.8 provides a bar chart summarizing the number of accident reports that were filed each month (U.S. Coast Guard's Boating Safety Division website, August 2010). a. Are the data categorical or quantitative?

The following data show the number of rental cars in service for three rental car companies: Hertz, Avis, and Dollar. The data are for the years 2007-2010 and are in thousands of vehicles (Auto Rental News website, May 15, 2011).

$$\begin{array}{lllllllllll} & & \text{ Cars in Service (1000s) } \\ Company & 2007 & 2008 & 2009 & 2010\\ Hertz & 327 & 311 & 286 & 290 \\ Dollar & 167 & 140 & 106 & 108 \\ Avis & 204 & 220 & 300 & 270 \end{array}$$

a. Construct a time series graph for the years 2007 to 2010 showing the number of rental cars in service for each company. Show the time series for all three companies on the same graph.

b. Comment on who appears to be the market share leader and how the market shares are changing over time.

c. Construct a bar chart showing rental cars in service for 2010. Is this chart based on cross-sectional or time series data?