The number of cell phones (CP) in the United States has been growing according to the following model CPt = CP0(1 + g)t where g is the growth rate and CP0 is the number of cell phones (in thousands) in 1995. After linearizing this model by a log transformation, we have ln CPt = ln CP0 + t ln(1 + g) and we obtain the following result as regression estimate ln CPt = 8.5 + 0.23t t = 1 for 1995
(a) What is the rate of growth of cell phones?
(b) What was the number of cell phones in use in the year 1995?
(c) Write the exponential equation and estimate the number of cell phones in use for the year 2012.