Cost of a Super Bowl 30-sec advertisement:
$42,000 in 1967
$345,000 in 1982
$2.05 million in 2001
$2.2 million in 2003

>	Pts:=[[1967,42000],[1982,345000],[2001,2.05*10^6],[2003,2.2*10^6]];

>	p1:=plot(Pts,labels=[year,"cost($)"]): p2:=plot(Pts,labels=[year,"cost($)"],style=point,color=blue,symbolsize=20): plots[display](p1,p2);

>	slope_1:=(345000-42000)/(1982-1967); slope_2:=(2.05*10^6-345000)/(2001-1982); slope_3:=(2.2*10^6-2.05*10^6)/(2003-2001);

What are the appropriate units for these slope values?
What would you predict for the cost of a 30-second advertisement in next year's Super Bowl?