15.10 The following data represent x=boat sales and y=boat trailer sales from 1995 through 2000.

year
boat sales
boat trailer sales

thousands
thousands
1995
649

207

1996
619

194

1997
596

181

1998
576

174

1999
585

168

2000
574

159



a) determine the least-squares regression line and interpret its slope
b) estimate, for a year during which 500,000 boats are sold, the number of boat trailers that would be sold.
c) what reasons might explain why the number of boat trailers sold per year is less then the number of boats sold per year?