Estimate the number of cell phone subscribers in 2008. Round to the nearest tenth.

For this case we have an exponential function of the form:

Where,

A: initial number of subscribers

b: rate of change

x: number of years

Part A:

The equation modeling the problem is given by:

For the year 2008 we have x = 2.

Substituting values:

Part B:

For the year in which the company reaches 278 million we have

Thus, the company reaches 278 million in the year 2009.