Chapter 1 Review Exercises

section 1.2

Refer to the following table for Exercises 1–3. The table contains information on some sports cars, as reported by the Environmental Protection Agency for model year 2014.

Make/Model Cylinders Transmission Combined
mileage
Chevrolet
Corvette		 8 Manual 21
Ferrari 458
Italia		 8 Automatic 14
Honda CR-Z 4 Manual 34
Jaguar F
Convertible		 6 Automatic 23
Porsche
Boxster S		 6 Automatic 24

Question 1.166

1. Use the table of sports cars to find each of the following.

  1. List the elements.
  2. Identify the variables.

1.99.1

(a) Make/Models: Chevrolet, Corvette, Ferrari 458 Italia, Honda CR-Z, Jaguar F Convertible, Porsche Boxster S (b) Cylinders, transmission, combined mileage

Question 1.167

2. Use the table of sports cars to answer the following.

  1. Identify the qualitative variables.
  2. Identify the quantitative variables.
  3. For each variable, state the level of measurement.

Question 1.168

3. Provide the observation for the Chevrolet Corvette.

1.99.3

8, manual, 21

Question 1.169

4. The following table contains population figures for the five most populous states.

State Pop. (1960,
in 1000s)		 Pop. (2013,
in 1000s)		 Increase
California 15,717 38,333 22,616
Texas 9,580 26,448 16,868
New York 16,782 19,651 2,869
Florida 4,952 19,553 14,601
Illinois 10,081 12,882 2,801
  1. Identify the elements and the variables.
  2. Are the variables qualitative or quantitative?
  3. Provide the observation for the state of Florida.
  4. Which three states had the largest population increases? Which two states had the smallest population increases?

Question 1.170

5. An electrical company has developed a new form of light bulb that it claims lasts longer than current models. The company has 1 million bulbs in its inventory. Consider the population average lifetime.

  1. What is the only way to find out the population average lifetime of the 1 million bulbs in the inventory?
  2. Suppose someone who worked for you wrote you a memo suggesting that it was crucial to know the exact value of the population average lifetime of all 1 million new light bulbs. How would you respond? What might you suggest instead?

1.99.5

(a) Turn on all 1 million light bulbs, leave them all on until they burn out, compute the average of all bulb lifetimes. (b) Use the average lifetime of a sample to estimate the average lifetime of the population.

37

section 1.3

Question 1.171

6. Refer to the Literary Digest poll discussed in Section 1.3.

  1. What was the target population?
  2. What was the potential population?
  3. What was the sample?
  4. Discuss whether the sample was similar to the target population in all important characteristics.

Question 1.172

7. Suppose you are interested in finding out how the statistics grades for your class compare with those of the college as a whole.

  1. Would you use an experimental study or an observational study?
  2. Discuss how this study situation would preclude effective randomization.

1.99.7

(a) Observational study (b) It would be impractical to randomly reassign people to a statistics class after classes have started.

Question 1.173

8. A long-running television advertisement claimed that “Three out of four dentists surveyed recommend sugarless gum for their patients who chew gum.”

  1. If in fact only four dentists were surveyed, which of the study factors were violated?
  2. Use this situation to discuss why replication is important.

Question 1.174

9. Suppose we are interested in determining whether differences exist in the cognitive levels of children from single-parent families and those from two-parent families. Would we use an observational study or an experimental study? Clearly describe why.

1.99.9

Observational; it would be impossible to randomly assign a child to come from a single-parent family or a two-parent family.