Stat 104 intro

A city council member wanted to know how her constituents felt about a planned rezoning. She randomly selected 75 names from the city phone directory and conducted a phone survey.

• The population is everyone listed in the city phone directory; the sample is the 75 people selected

• The population is residents of the city; the sample is the registered voters in the city.

• The population is registered voters in the city; the sample is everyone listed in the city phone directory.

Lucio wants to know whether the food he serves in his restaurant is within a safe range of temperatures. He randomly selects 70 entrees and measures their temperatures just before he serves them to his customers.

• The population is all of the hot entrees Lucio serves; the sample is the entrees that are a safe temperature.

• The population is the 70 selected entrees; the sample is the entrees that are a safe temperature.

• The population is all of the entrees Lucio serves; the sample is the 70 selected entrees.

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.

• The population is every possible point on the car; the sample is the 30 selected points.

• The population is every car at the factory; the sample is the 1 car she is curious about.

• The population is every car at the factory; the sample is the 30 selected points.

The state Department of Transportation wants to know about out-of-state vehicles that pass over a toll bridge with several lanes. A camera installed over one lane of the bridge photographs the license plate of every tenth vehicle that passes through that lane.

• The population is all of the vehicles that pass over the toll bridge; the sample is vehicles from the lane with the camera.

• The population is all of the vehicles that pass through the lane with the camera; the sample is the group of every tenth vehicle that passes through the lane.

• The population is all of the out-of-state vehicles; the sample is the vehicles that pass over the toll bridge.

Examples of categorical variables

Examples of quantitative variables