Final answer:
Questioning every 14th customer leaving a theatre about the movie they had seen is an example of systematic sampling.
Step-by-step explanation:
A systematic sample is a sampling method where every nth element in a population is selected for inclusion in the sample. In this case, the question asks about questioning every 14th customer leaving a theatre about the movie they had seen. This is an example of systematic sampling because every 14th customer is being selected as part of the sample. The process of systematic sampling ensures that the sample is representative of the entire population.
For example, if there were 140 customers leaving the theatre, the systematic sample would include customers numbered 14, 28, 42, 56, 70, 84, 98, 112, and 126.