The gates of an amusement park are closely monitored to determine whether the number of people in the amusement park ever poses a safety hazard.
On a certain day, the rate at which people enter amusement park is modeled by the function
e(x) = 0.03x3 + 2, where the rate is measured in hundreds of people per hour since the gates
opened. The rate at which people leave the amusement park is modeled by the function
l(x) = 0.5x + 1, where the rate is measured in hundreds of people per hour since the gates
opened.
What does (e – l)(4) mean in this situation?