Thread: Cost function

I'm having issues remembering how to create cost functions:

For a long-distance phone call, a hotel charges $9.89 for the first minute and $0.90 for each additional minute or fraction thereof. A formula for the cost is given below, where t is the time in minutes

So the function is ?

C(t)=9.89-0.90[[-(t-1)]]

Do I just distribute that out?


Use a graphing utility to graph the cost function for 0 < t ≤ 5.

How do I set the paramaters for this requirement to graph this on my calculator ?

Originally Posted by Jerry99

I'm having issues remembering how to create cost functions:
For a long-distance phone call, a hotel charges $9.89 for the first minute and $0.90 for each additional minute or fraction thereof. A formula for the cost is given below, where [I]t is the time in minutes
So the function is ?
C(t)=9.89-0.90[[-(t-1)]]

I would use the ceiling function:

Hello, Jerry99!

That cost function is scary . . .

For a long-distance phone call, a hotel charges $9.89 for the first minute
and $0.90 for each additional minute or fraction thereof.
A formula for the cost is given below, where is the time in minutes

So the function is ?

C(t) = 9.89 - 0.90[[-(t-1)]] . Weird!


Use a graphing utility to graph the cost function for 0 < t ≤ 5.

How do I set the paramaters for this requirement to graph this on my calculator?

The hotel charges $9.89 for the first minute.
It charges $0.90 per minute for the other minutes.
The "or fraction thereof" means that they will round up when a fraction is involved.
. . Hence, the remaining time is minutes (ceiling function).

The cost is: .


The graph looks like this.

Code:

          |
   $13.49 +                       o=====♠
          |                       :     :
          |                       :     :
   $12.59 +                 o=====♠     :
          |                 :     :     :
          |                 :     :     :
   $11.69 +           o=====♠     :     :
          |           :     :     :     :
          |           :     :     :     :
   $10.79 +     o=====♠     :     :     :
          |     :     :     :     :     :
          |     :     :     :     :     :
    $9.89 o=====♠     :     :     :     :
          |     :     :     :     :     :
          |     :     :     :     :     :
          |     :     :     :     :     :
      - - * - - + - - + - - + - - + - - + - -
          0     1     2     3     4     5  minutes

Ok thanks guys