Question

In 1985, there were 285 cell phone subscribers in Arlington. The number of subscribers increased by 75% per year since 1985. Find the number of subscribers in 2008.

Answer 1

The number of subscribers in 2008 is 110,845,988

Explanation:

The number of cell phone subscribers in Arlington, in t years after 1985, can be modeled by the following equation.

`N(t) = N(0)(1+r)^(t)`

And which N(0) is the number of subscribers in 1985 and r is the rate it increases per year, as a decimal.

In 1985, there were 285 cell phone subscribers in Arlington.

This means that
`N(0) = 285`

The number of subscribers increased by 75% per year since 1985.

This means that
`r = 0.75`

So

`N(t) = 285(1.75)^(t)`

Find the number of subscribers in 2008.

2008 is 2008-1985 = 23 years after 1985. So we have to find N(23).

`N(23) = 285(1.75)^(23) = 110,845,988`

The number of subscribers in 2008 is 110,845,988