Final answer:
The question asks to identify the sampling method in given scenarios, with answers ranging from convenience sampling for easy-to-access subjects to systematic sampling when a system or pattern is used to select participants.
Step-by-step explanation:
The student's question involves identifying the type of sampling method used in various scenarios. In situation (a), where a woman only asks travelers who are sitting and not busy, the method is convenience sampling because she selects individuals who are easily accessible and most convenient to her.
For (b), when a teacher selects certain rows to answer homework problems, this is an example of systematic sampling, as she is using a system (specific rows) to choose her sample. Situation (c), where an administrative assistant asks the first 100 undergraduate students they encounter about tuition costs, also constitutes convenience sampling as the sample is selected based on ease of access. Finally, in (d), a medical researcher interviews every third cancer patient; this is systematic sampling because the researcher follows a system or pattern (every third patient) to select participants. These methods are part of research design in statistics, a crucial element in collecting data for analysis.