Bluman A.G. Elementary Statistics- A Step By Step Approach

Instructor’s Section Answers25. H 0 : the numbers occur at random and H 1 : the nullhypothesis is not true. There are 16 runs, and since this isbetween 9 and 21, the null hypothesis is not rejected.There is not enough evidence to reject the null hypothesisthat the numbers occur at random.Chapter 14Exercises 14–11. Random, systematic, stratified, cluster2. Samples can save the researcher time and money. Theyare used when the population is large or infinite. They areused when the original units are to be destroyed, such asin testing the breaking strength of ropes.3. A sample must be randomly selected.4. Random numbers are used to ensure every element of thepopulation has the same chance of being selected.5. Talking to people on the street, calling people on thephone, and asking your friends are three incorrect ways ofobtaining a sample.6. Over the long run each digit, 0 through 9, will occur withthe same probability.7. Random sampling has the advantage that each unit of thepopulation has an equal chance of being selected. Onedisadvantage is that the units of the population must benumbered; if the population is large, this could besomewhat time-consuming.8. Systematic sampling has an advantage in that once thefirst unit is selected, each succeeding unit selected hasbeen determined. This saves time. A disadvantage wouldbe if the list of units was arranged in some manner so thata bias would occur, such as selecting all men when thepopulation consists of both men and women.9. An advantage of stratified sampling is that it ensuresrepresentation for the groups used in stratification;however, it is virtually impossible to stratify thepopulation so that all groups are represented.10. Clusters are easy to use since they already exist, but it isdifficult to justify that the clusters actually represent thepopulation.11–20. Answers will vary.Exercises 14–21. Flaw—biased; it’s confusing.2. Flaw—the purpose of the question is unclear. You couldlike him personally but not politically.3. Flaw—the question is too broad.4. Flaw—none. The question is good if the respondentknows the mayor’s position; otherwise his position needsto be stated.5. Flaw—confusing words. How many hours did you studyfor this exam?6. Possible order problem—ask first, “Do you use artificialsweetener regularly?”7. Flaw—confusing words. If a plane were to crash on theborder of New York and New Jersey, where should thevictims be buried?8. Flaw—none.9. Answers will vary.10. Answers will vary.Exercises 14–31. Simulation involves setting up probability experimentsthat mimic the behavior of real-life events.2. Answers will vary.3. John Von Neumann and Stanislaw Ulam4. Using the computer to simulate real-life situations cansave time, since the computer can generate randomnumbers and keep track of the outcomes very quicklyand easily.5. The steps are as follows:a. List all possible outcomes.b. Determine the probability of each outcome.c. Set up a correspondence between the outcomes and therandom numbers.d. Conduct the experiment by using random numbers.e. Repeat the experiment and tally the outcomes.f. Compute any statistics and state the conclusions.6. Random numbers can be used to ensure the outcomesoccur with appropriate probability.7. When the repetitions increase, there is a higherprobability that the simulation will yield more preciseanswers.8. Use a table of random numbers. Select 40 randomnumbers. Numbers 01 through 16 mean the person isforeign-born.9. Use three-digit random numbers; numbers 001 through681 mean that the mother is in the labor force.10. Select two-digit random numbers in groups of 5. For oneperson, 01 through 70 means a success. For the otherperson, 01 through 75 means a success.11. Select 100 two-digit random numbers. Numbers 00 to 34mean the household has at least one set with premiumcable service. Numbers 35 to 99 mean the householddoes not have the service.12. Use the odd digits to represent a match and the evendigits to represent a nonmatch.13. Let an odd number represent heads and an even numberrepresent tails. Then each person selects a digit at random.14–24. Answers will vary.IS–73