Population Sampling Inferences

_______ is the entire group of objects or individuals considered for a survey.

• Sample

• Quartile

• Random Sample

• Population

A sample should be

• representative of  only middle school students only

• a very large group

• representative of the population

• representative of people who volunteer

What is the population?

• All students at HMS

• All students in 4th period

• The 10 students Ms. Falls picks

• All students in 7th grade

What is the sample?

• All students at HMS

• All students in 4th period

• The 10 students Ms. Falls picks

• All students in 7th grade

A study on a random sample of 250 cars passing through a toll booth shows that 75 cars are from out of state. Predict the number of out-of-state cars among 1000 cars passing through the toll booth.

• 300

• 250

• 200

• 350

Answer explanation

To predict the number of out-of-state cars among 1000 cars, use the ratio from the sample: 75/250 = x/1000. Solving for x gives 300.

Population or Sample?

A quality control engineer is curious about the thickness of paint on a car at her factory. She randomly selects 30 points on the car and measures the paint thickness at each of those points.

• Population

• Sample

What is the entire group studied called?

• sample

• population

• class

• experiment

There are 45 people working in a particular building. A survey on dietary habits is conducted by giving every third person in the building a questionnaire to fill out. From the questionnaire, the researcher obtains a score on the dietary habits of the 15 people.

What is the number of members in the population?

Mathematical Equivalence

ON

A survey conducted on a random sample of 120 people in a town shows that 60 people own a pet. If the town has 4800 people, how many people in the town are likely to own a pet?

• 2400

• 1200

• 1800

• 3000

Answer explanation

Since 60 out of 120 people own a pet in the sample, we can estimate that 2400 out of 4800 people in the town likely own a pet (60/120 = 2400/4800). Therefore, the correct answer is 2400.

In a random sample of 20 students from a class, 8 students said they participate in after-school sports. Predict the total number of students participating in after-school sports in a school of 400 students.

• 160

• 80

• 120

• 200

Answer explanation

To find the total number of students participating in after-school sports in a school of 400 students, we can use the ratio method. 8 students out of 20 participate, so 8/20 = x/400. Solving for x gives us 160 students.