# Functions as Models of Real-Life Situations

Functions can be used to predict the outcomes of certain physical events or real-life situations.Example

The graph shows the number of music CDs sold at various prices. At what price should the CDs be marked to sell the maximum number of CDs?

- 0
- 5
- 10
- 15
- 20

Solution

As you read the graph from left to right, it shows that sales initially increase rapidly and then slow to a maximum of about 300,000.

From there, sales drop precipitously and then slowly approach zero as the price continues to increase.

From the graph, sales of 300,000 units on the *y*-axis correspond to a price of about $10 on the *x*-axis.

The answer is (C).