[EX02-078] Does everything increase, every year? Sometimes it seems like it! The annual percentage rate of increase in motor-fuel consumption for 2002 to 2003 is listed in the following table by U.S. state. Notice that the consumption did not increase in every state and not all states reported.

1.8 16.9 1.8 0.1 2.8 0.4 2.6 0.8 6.3 2.7 1.1 0.1 4.6 0.4 0.2 0.9 2.8 1.5 3.6 10.8 2.3 0.5

1 1 2.9 1.6 1.2 0.1 5.5 0.2 8.9 2.1 0.5 0.1 2.9 0.5 3.7 1.1 1.3 0 1.3 2.4 0.9 0.1 Source: U.S. Department of Transportation, Federal Highway Administration

a. Explain the meaning of negative and positive values, large and small values, values near zero, and values not near zero.

b. Examine the data in the table. What do you anticipate the distribution of “percent change”

will look like? What do you think the mean

“percent change” will be? Justify your estimate, without any preliminary work or calculations.

c. If you expect very little or no change, what value will the mean have? Explain.

d. Construct a histogram of the percent of change.

e. Calculate the mean percent of changes in consumption from 2002 to 2003.

f. The Federal Highway Administration reported the percentage increase for the entire United States as 0.5586 of 1%. The value calculated for the mean in part e is not the same. Explain how this is possible.