Which measurement level (nominal, ordinal, interval, ratio) is each of the following variables? Explain.
a. Number of passengers on Delta Flight 833.
b. Waiting time (minutes) after gate pushback before Delta Flight 833 takes off.
c. Brand of cell phone owned by a cabin attendant on Delta Flight 833.
d. Ticket class (first, business, or economy) of a randomly chosen passenger on Delta Flight 833.
e. Outside air temperature (Celsius) when Delta Flight 833 reaches 35,000 feet.
f. Passenger rating (on 5-point Likert scale) of Delta's in-flight food choices.