The number of cell phone subscribers in a country in the years 2000-2005 was projected to follow the equation n(t) = 39t + 64 million subscribers in year t (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 + 72)e^0.2t million dollars.

(a) determine when to the nearest 0.1 year the revenue was projected to peak.

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