# Rational Function Application Question

1. Mar 8, 2010

### Cuisine123

1. The problem statement, all variables and given/known data
A home security system costs $9/month in electricity costs (you may assume this is a fixed cost over the duration of the time involved in this question). A new security system costs$1500 to purchase and lasts for 8 years.

Determine a rational function that gives the annual cost of a security system as a function of the number of years you own the system. Using this function determine the average annual cost of the security system given above.

2. Relevant equations
n/a

3. The attempt at a solution
I got C(x)=(1500+108n)/n, where n is the number of years.
What would be the "average annual cost" of the security system given above?

2. Mar 9, 2010

### tiny-tim

Hi Cuisine123!
That is the "average annual cost", isn't it?

3. Mar 9, 2010

### Cuisine123

The questions says, "Determine a rational function that gives the annual cost of a security system as a function of the number of years you own the system. Using this function determine the average annual cost of the security system given above."

C(x)=(1500+108n)/n, where n is the number of years, would be the rational function that gives the annual cost of the security system.

What about the average annual cost of the security system given above ?
Would it be C(8)=(1500+108(8))/8?