Question

cruising altitude is the altitude in which an airplane flies the majority of its flight. The plane generally reaches cruising altitude of a short time after takeoff. The plane begins it’s descent some minutes before it reaches it’s destination

Answer 1

1. Im not exactly sure what the question is asking for, if you reply with a clarification I may be able to give you a better answer.
My best interpretation: The intervals are represented as line segments, either increasing, decreasing, at rest, or at a constant speed. With change of the action of the plane comes with a different interval.
2. The two quantities are the time and the altitude, who represent the altitude of the plane over the course of time.
3. The plane is at cruising altitude when the plane is at it’s relative maximums and is at a constant speed during those relative maximums.
4. At interval four, the plane is at rest. Unloading passengers, refueling, unloading cargo, loading other cargo, and loading other people.
5. At interval 1 and 5, the intervals are increasing. 5 has a steeper slope, which means the plane increases altitude at a faster rate as it reaches cruising height at a faster rate than interval 1.
6. The slope of an interval represents the altitude of the plane, whether increasing, constant, decreasing, or at rest, over a course of time in hours.