1) Determine whether the evaluated group is a population or a sample

a) Based on a randomly selected group of 500 patients with high cholesterol, it was found that 67% have heart disease. Is this a population or a sample; explain your answer.

This is a sample, or a subgroup of the population being studied. The population is all people with high cholesterol. Since the group of 500 who were selected is not all people with high cholesterol, the data represents that of a sample. The data from this sample will be used to generalize information about the population.

b) An investigation of 150 randomly selected local restaurants concluded that 42% of local restaurants have serious health code violations. Is this a population or a sample; explain your answer.

The local restaurants are part of a sample. The population is all local restaurants. Since it is unreasonable to collect data from all the restaurants, a sample is randomly selected from the population, using local restaurants as a population parameter to identify a sample for the study.

2) Determine whether the given value is a statistic or a parameter.

c) A researcher determines that 42.7% of all downtown office buildings have ventilation problems. Is this a statistic or a parameter; explain your answer.

In this scenario, it is a statistic formed from raw data that the researcher calculated presumably from a sample. The number is descriptive of the group that was included in the study, and is applied to the total group.

d) After taking the first exam, 15 of the students dropped the class. Is this a statistic or a parameter; explain your answer.

This is a parameter which explains an attribute of the entire class. The whole class, at the time of the exam, is the population and students dropping the class a parameter specific to the whole group.

3) Identify the type of sampling used.

e) A tax auditor selects every 1000th income tax...