Suppose the price of a first-class stamp was 4¢ for the first time in 1958 and 44¢ in 2009. Find a simple exponential function of the form

Question

y = ab^t that models the cost of a first-class stamp for 1958–2009. (Let
t = 0 correspond to 1958. Assume y is in dollars. Round your value for b to four decimal places.)

Also how to predict value for 2020

Answer 1

there are 51 years from 1958 to 2009
So, you want b such that
4b^51 = 44/4
b^51 = 11/4
b = (11/4)^(1/51) = 1.02003