1. A computer outlet store receives a shipment of 1000 computer chips. The owner decides to randomly choose 20 chips and test them. What is the population in this study? What is the sample?
2. Three different acids are used in removing film from a machine part. A plant manager wants to test which removes the film in the least amount of time. Nine parts are chosen and each acid is used on three parts. The time it takes to remove the film is measured for each. Is this an observational study or an experiment? Explain why.
3. A manufacturing corporation has 20 plants in 20 different states. A new quality control process will be tested at 5 of these plants. From the list below, use the random digits table in your text (p. 539) to randomly sample 5 plants from the 20. Write out your exact method so that anyone unfamiliar with this process will fully understand.
| Alabama | Connecticut | Delaware | Florida |
| Georgia | Indiana | Kentucky | Massachusetts |
| Michigan | Mississippi | Montana | Nevada |
| New Hampshire | North Dakota | Oklahoma | South Carolina |
| Texas | Utah | Vermont | Washington |
4. A researcher has 12 experimental units to use in a study to compare 4 different methods of surface etching. Suppose that the units have been labeled 1, 2, ..., 12. Costruct a random assignment of the units to the 4 treatments (3 per treatment). Explain your method.
5. Suppose four different methods are used to refine an oil product. Each method may result in a different viscosity of the product. Each method is applied to one barrel of oil at a time which results in one batch of product. A company wants to use the method which results in the lowest viscosity and they want to design an experiment to test this.
a) What are the experimental units in this experiment?
b) If the company is willing to spend enough money for only producing 32 batches, how many replications will we have?
c) What are the treatments and how many do we have?
d) What is the response variable?
e) Suppose 3 different plants use each of these 4 methods. Each plant is willing to be involved in the experiment. Each plant will produce 16 batches. Explain how the use of blocking should be incorporated into our experiment. Give a plan for conducting this experiment by explaining how each plant will use which method. Be sure to include a randomization scheme.
6. A rigorous test has been designed for metal compounds. This test increases the rate of oxidation of these metals to represent years of exposure to weather. Four different metal compounds are under consideration for manufacturing a machine component and each will be tested for oxidation.
a) What is the treatment in this experiment?
b) What is the response variable?
c) If we have 5 samples of each metal compound, how many experimental units do we have total?