Chapter 3.3, Problem 92E

Movie Advertising The percentage of movie advertising as a share of newspapers’ total advertising revenue from 1995 to 2004 can be approximated by

$p\left(t\right)=\{\begin{array}{l}0.07t+6.0\text{ if }t\le 4\\ -0.3t+17.0\text{ if }t>4,\end{array}$

Where t is time in years since 1995.

a. Compute ${\lim }_{t\to 4^{-}}p\left(t\right)$

and ${\lim }_{t\to 4^{+}}p\left(t\right)$, and interpret each answer. [HINT: See Example 3.]

b. Is the function f continuous at $t=4$? What does the answer tell you about movie advertising expenditures?