1. Rational Functions in the Real World

2. Medical Example
Before surgery a patient might be injected with some medication.
When the concentration of the drug in the bloodstream is at a desired level the operation will begin.
You can model the concentration of the drug in the patient’s bloodstream using a rational function.

3. Medical Example Cont’d
Here is a hypothetical rational function representing the concentration of a drug in the patient’s bloodstream with respect to time.

4. Medical Example Graph
C(t) t

5. Medical Example Cont’d
Being able to analyze this rational function can help a nurse or doctor determine when the drug will wear off on the patient.
Imagine not knowing how to do this and having a patient wake up during surgery.

6. Economic Example
You can use rational functions to model what are known as average cost functions.
Average cost functions can help a business determine the cost of producing a certain product.

7. Economic Example Cont’d
Suppose your company makes light bulbs and you want to determine the average cost of making light bulbs.

8. Economic Example Cont’d
You can model the average cost function for making light bulbs using the rational function shown below.
fixed cost to run business
cost of each light bulb
number of light bulbs produced

9. Economic Example Cont’d
Using this rational function, you can model how much it will cost to make light bulbs, which can be important information for a businessman.