2.1 Exercise 93

Suppose that average annual income (in dollars) for the years 1990 through 1999 is given by the linear function: $I \left(x\right) = 1054 x + 23 , 286 ,$ where $x$ is the number of years after 1990. Which of the following interprets the slope in the context of the problem?

1. As of 1990, average annual income was $23,286.
2. In the ten-year period from 1990–1999, average annual income increased by a total of $1,054.
3. Each year in the decade of the 1990s, average annual income increased by $1,054.
4. Average annual income rose to a level of $23,286 by the end of 1999.