A factory produces plastic cell phone cases. To fit properly, each case must have a width between 53.5 and 54.5 millimeters. The quality control manager for the factory collects a random sample of 100 cases and determines that the widths are normally distributed, with a mean width of 54.2 millimeters and a standard deviation of 0.3 millimeter.

Step-by-step explanation:

Hello!

To easily identify these items you have to ask yourself the following questions:

1)

Who I want to study?

Workers age 16 or older from Arizona

The population of the study is all the experimental units in existence, in this case

Population: Workers age 16 or older from Arizona

The sample is a part of the population of interest, normally representative of the population and randomly selected, that the researcher uses to study.

In this case, the sample taken is: 5000 Arizona workers age 16 or older

The individual is defined by each experimental unit that conforms the sample, in this case

Individual: One Arizona worker age 16 or older.

2)

What do I want to study?

The percentage of people who use the train to get to work

The variable of interest is the characteristic that the researcher will measure in each experimental unit:

Variable: "The percentage of Arizona workers age 16 or older who use the train to get to work"

I hope this helps!