Sampling and Populations

To determine how many people in a town support a new tax levy, 200 people are randomly selected from a phone book and then surveyed over the phone. Identify each sample as biased or unbiased and describe its type.

• unbiased; systematic random sample

• unbiased; simple random sample

• biased; convenience sample

• biased; voluntary response sample

To determine the number of households in a town that recycle, 40 households from the same street are polled. Identify each sample as biased or unbiased and describe its type.

• biased; convenience sample

• biased; voluntary response sample

• unbiased; stratified random sample

• unbiased; systematic random sample

To determine the usual demand of a Web site, the number of users currently visiting the Web site is recorded every hour. Identify each sample as biased or unbiased and describe its type.

• unbiased; stratified random sample

• biased; convenience sample

• unbiased; systematic random sample

• biased; voluntary response sample

The yearbook staff wanted to find out how many students would buy a yearbook. So, the staff surveyed 15 students who were in the school library after school. The results are in the graph. Is this sampling method valid? If so, about how many of the 1287 students in the school will buy yearbooks?

• valid; 343 students

• valid; 944 students

• valid; 1100 students

• not valid

They randomly surveyed 200 patrons and 6 patrons responded that they would regularly check out books from an enlarged print section. If the library has a total of 3200 patrons, how many people can they expect to regularly check out books from an enlarged print section?

• 96 people

• 960 people

• 206 people

• 6 people

To determine whether students will attend the spring craft fair, Andrea surveyed the art classes. Identify the sample as biased or unbiased and describe its type.

• unbiased, simple random sample

• unbiased, stratified random sample

• biased, voluntary response sample

• biased, convenience sample

During production, a manufacturer of clock radios pulls every 75th radio from the assembly line to check for overall quality. Identify the sample as biased or unbiased and describe its type.

• unbiased, systematic random sample

• biased, voluntary response sample

• unbiased, simple random sample

• unbiased, stratified random sample