Page 199 - Math Course 3 (Book 2)

Sampling and Bias

Skill Practice!

Identify each sample, suggest a population from which it was selected, and state whether it is unbiased
(random) or biased. If unbiased, classify the sample as simple, stratified, or systematic. If biased, classify as
convenience or voluntary response.
1. LANDSCAPING A homeowner is concerned about the quality of the topsoil in the back yard.
The back yard is divided into 5 equal sections, and then a 1-inch plug of topsoil is randomly removed from
each of the 5 sections. The soil is taken to a nursery and analyzed for mineral content.

2. HEALTH A hospital’s administration is interested in opening a gym on the premises for all its employees.
They ask each member of the night-shift emergency room staff if he or she would use the gym, and if so,
what hours the employee would prefer to use it.

3. POLITICS A senator wants to know her approval rating among the constituents in her state. She sends
questionnaires to the households of 1000 registered voters in her party.

4. MANUFACTURING A company that produces motherboards for computers randomly selects 25 boxed
motherboards out of a shipment of 1500, and then tests each selected motherboard to see that it meets
specifications.

5. GOVERNMENT The first 100 people entering a county park on Thursday are asked their opinions on a pro
posed county ordinance that would allow dogs in county parks to go unleashed in certain designated areas.

6. MUSIC To determine the music preferences of their customers, the owners of a music store ask 10
customers who have expressed interest to participate in an in-store interview in which they listen to new
CDs from artists in all music categories.

7. LIBRARIES A community library asks every tenth patron who enters the library to name the type or genre of
book he or she is most likely to borrow. They conduct the interviews from opening to closing on three days
of the week. They will use the data for new acquisitions.

8. COMPUTERS To determine the number of students who use computers at home, the high school office
chooses 10 students at random from each grade, and then interviews the students

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