Problem
Overdraft fees have become an important piece of a bank's total fee income. Suppose the following table gives the bank revenue from overdraft fees (in billions of dollars) from 2004 through 2009. Here, x = 4 corresponds to 2004.
Year, x 4 5 6 7 8 9
Revenue, y 24.5 28 33 35 37 38
(a) Find an equation of the least-squares line y for these data.