With computer security always a hot-button issue, demand is growing for technology that authenticates and authorizes computer users. The following table gives the authentication software sales (in billions of dollars), including projections, from 1999 through 2004 (x = 0 represents 1999).

Year, x	0	1	2	3	4	5
Sales, y	2.5	3	4.5	4.5	5.5	5.5

(a) Find an equation of the least-squares line for the data. (Round your numerical values to two decimal places.) y =

(b) Use the results in part (a) to estimate the sales for 2007, assuming the projection is accurate. (Round your answer to two decimal places.) $ billion