Draw a UML class diagram showing an inheritance hierarchy containing classes that represent different types of airplanes. Show some appropriate variables and method names for at least two of these classes.

A primary key can be left empty in a record when the database is saved

Indicate whether the statement is true or false

1. __________ is total execution time (for all programs) divided by total elapsed time, and is often expressed as a percentage.

a. Throughput b. Turnaround c. Response time d. none of the above