1. The actual number of help-wanted ads in a local newspaper was 1682, 1963, 2451, and 3205 for quarters I through IV, respectively, of the preceding year. The cor- responding deseasonalized values are 2320, 2362, 2205, and 2414, respectively. Based on this information, what seasonal index is associated with each quarter?
2. The trend equation yˆ 5 2050 1 12x has been developed for the number of vehicles using the ferry ser- vice at a national seashore each year. (The years have been coded so that 1997 corresponds to x 5 1.) If the seasonal indexes for quarters I through IV are 55.0, 130.0, 145.0, and 70.0, respectively, estimate the usage volume for each quarter of 2014.
3. The trend equation yˆ 5 150 1 12x 1 0.01x2 has been developed for annual unit sales of a filtering system component used by municipal water authorities. The years have been coded so that 2001 corresponds to x 5 1. If the seasonal indexes for quarters I through IV are 85.0, 110.0, 125.0, and 80.0, respectively, estimate the unit sales for each quarter of 2015.
4. The U.S. Energy Information Administration reports the following prices for regular unleaded gasoline in Germany from 2003 through 2008. Source: U.S. Energy Information Administration, Annual Energy Review 2008, p. 321.