The Accuweather Corporation manufactures barometers and thermometers for weather forecasters.

The Accuweather Corporation manufactures barometers and thermometersfor weather forecasters. In an attempt to forecast its future needs for mercury,Accuweather’s chief economist estimated average monthly mercury needs as:N = 500 + 10Xwhere N = monthly mercury needs (units) and X = time period in months(January 2005 = 0). The following monthly seasonal adjustment factors havebeen estimated using data from the past ve years:Month Adjustment FactorJanuary 15%April 10%July -20%September 5%December -10%a. Forecast Accuweather’s mercury needs for January, April, July, September,and December of 2007.b. The following actual and forecast values of mercury needs in the month ofNovember have been recorded:Year Actual Forecast2004 456 4802005 324 3602006 240 240What seasonal adjustment factor should the rm use for November?