# Calculus

posted by
**Christina**
.

The number N of US cellular phone subscribers (in millions) is shown in the table. (Midyear estimates are given.)

t 1996 1998 2000 2002 2004 2006

N 44 69 109 141 182 233

(a) Find the average rate of cell phone growth between the following years. In each case, include the units. (Round your answers to one decimal place.)

(i) from 1996 to 2004

million phones/yr

(ii) from 2002 to 2004

million phones/yr

(iii) from 2000 to 2002

million phone/yr

(b) Estimate the instantaneous rate of growth in 2002 by taking the average of the two average rates of change in (ii) and (iii). What are its units?

______million phones/yr