Question

question #7
describe the sampling technique used in the study below.
a class of statistics students are told they will take an exam at the end of the course. the exam contains a multiple - choice section. a study is conducted to determine if the students felt they had enough time to complete the multiple - choice section after taking the exam. every school was selected from the list of all schools represented, and 10 students from each school were asked if he or she thought the time allowed to complete the multiple - choice section of the exam was adequate.

systematic sampling
stratified sampling
cluster sampling
probability sampling

question #8
to assess its employees views of new student fees imposed by the state legislature, a university divided employees into two groups: those with at least 20 years, and those with fewer than 20 years, of service. a random sample was selected from each group and their views were obtained by telephone.
this method of sampling is likely to be:

biased, because the two groups are different in character.
unbiased, because it is an example of stratified random sampling.
biased, because systematic sampling should have been used to contact employees.
unbiased, because the population has been stratified by telephone number.

Explanation:

Question #7

Stratified sampling divides the population into subgroups (here, schools) and samples from each subgroup.

Stratified random sampling divides the population into strata (here, by years of service) and samples randomly from each stratum, which is unbiased.

Answer:

Stratified Sampling

Question #8