Suppose that the sales at Borders bookstores went from 70 million dollars in 1989 to 415 million dollars in 1993. What is the continuous percent growth rate, per year, of sales?

Answer 1

let sales be

S = 70 e^kt, where S in in millions and t is the number of years since 1989

so when t=4 , S = 415

415 = 70 e^(4k)
5.92857 = e^4k
4k = ln 5.92857
k = ln 5.92857)/4 = .4449

or 44.49% continuous growth.