For each of the following situations, decide what sampling method you would use. Provide an explanation of why you selected a particular method of sampling.
a. The major state university in the state is attempting to lobby the state legislature for a bill that would allow the university to charge a higher tuition rate than the other universities in the state. To provide a justification, the university plans to conduct a mail survey of its alumni to collect information concerning their current employment status. The university grants a wide variety of different degrees and wants to make sure that ­information is obtained about graduates from each of the degree types. A 5% sample of alumni is considered sufficient.
b. The Environmental Protection Agency (EPA) is required to inspect landfills in the United States for the presence of certain types of toxic material. The materials were sealed in containers and placed in the landfills. The exact location of the containers is no longer known. The EPA wants to inspect a sample of 100 containers from the 4,000 containers known to be in the landfills to determine if leakage from the containers has occurred.