Sampling and Population

Identify the Population:
Wicomico County Public Schools randomly selected 230 teachers to find out which technology resource it's teachers feel is the most effective.

• 230 Teachers

• All Wicomico County Teachers

• Students

• Wicomico County Public Schools

If I wanted to know how many blades of grass are inside the track, which sampling method could I use?

• Have my students count every blade of grass

• Guess

• Divide the grassy area into 1 inch sections, randomly pick several sections to count, average them together and multiply that by the total square inches.

To get valid results, a sample must be...

• biased

• unbiased

Identify the Sample:
A restaurant wants to know if their customers buy dessert when they eat out. As people leave the restaurant one evening, 20 people are surveyed at random. Eight people say they usually order dessert when they eat out. The restaurant concluded that most customers do not order dessert.

• 20 customers

• All customers

• 8 customers

• Dessert

Unbiased sampling is:

• when you choose the group you think will give you the answer you want, accept volunteers or survey by convenience

• when any member of the population is equally likely to be chosen for the sample

To determine how often people eat out, every tenth person entering a Chinese restaurant is surveyed.

• Biased Sample

• Unbiased Sample

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

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

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