The number of cell phone subscribers in a country in the years 2000-2005 was projected to follow the equationN(t) = 39t+65

million subscribers in yeart(t= 0 represents January 2000). The average annual revenue per cell phone user was $350 in 2000. If we assume that due to competition the revenue per cell phone user decreases continuously at an annual rate of 20%, we can model the annual revenue as

R(t) = 350(39t+65)e^0.2tmillion dollars.

(a) Determine when to the nearest 0.1 year the revenue was projected to peak. (Submit your answer in terms oft.)

yr

(b) Determine the revenue, to the nearest $1 million, at that time.

$million