Chapter 5 - Section 5.1 - Introduction to Polynomials and Polynomial Functions - Exercise Set - Page 326: 70

See below.

The leading coefficient of $f$ is $-0.87$, which is negative and the degree of $f$ is $3$, which is odd. Thus the function falls to the right. Thus at one point $f$ is going to be negative, thus the graph doesn't make sense because it is impossible to have a negative number of thefts.