Test Bank For Probability And Statistics For Engineering And The Sciences 8th Edition by Jay L. Devore

TestBank ForProbabilityAnd StatisticsForEngineering And
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, ss The Sciences 8th Ed by Jay L. Devore.
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Chapter 1 – Overview and Descriptive Statistics
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SHORT ANSWER
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1. Give one possible sample of size 4 from each of the following populations:
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a. All daily newspapers published in the United States
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b. All companies listed on the New York Stock Exchange
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c. All students at your college or university
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d. All grade point averages of students at your college or university
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ANS:

a. Houston Chronicle, Des Moines Register, Chicago Tribune, Washington Post
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b. Capital One, Campbell Soup, Merrill Lynch, Pulitzer
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c. John Anderson, Emily Black, Bill Carter, Kay Davis
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d. 2.58. 2.96, 3.51, 3.69 s s s s s s




PTS: 1

2. A Southern State University system consists of 23 campuses.
s s s s An administrator wishes to
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s s make an inference about the average distance between the hometowns of students and their
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s s campuses. Describe and discuss several different sampling methods that might be employed.
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s s Would this be an enumerative or an analytic study? Explain your reasoning.
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ANS:
One could take a simple random sample of students from all students in the California State
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University system and ask each student in the sample to report the distance from their
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hometown to campus.
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Alternatively, the sample could be generated by taking a stratified random sample by taking
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a simple random sample from each of the 23 campuses and again asking each student in
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the sample to report the distance from their hometown to campus.
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Certain problems might arise with self reporting of distances, such as recording error or poor
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recall. This study is enumerative because there exists a finite, identifiable population of
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objects from which to sample.
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PTS: 1

3. A Michigan city divides naturally into ten district neighborhoods. How might a real estate
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s s appraiser select a sample of single-family homes that could be used as a basis for
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s s developing an equation to predict appraised value from characteristics such as age, size,
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s s number of bathrooms, and distance to the nearest school, and so on? Is the study
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s s enumerative or analytic? s s s s




ANS:

One could generate a simple random sample of all single family homes in the city or a
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stratified random sample by taking a simple random sample from each of the 10 district
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neighborhoods. From each of the homes in the sample the necessary variables would be
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collected. This would be an enumerative study because there exists a finite, identifiable
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population of objects from which to sample.
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, PTS: 1

4. An experiment was carried out to study how flow rate through a solenoid valve in an
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s s automobile‘s pollution-control system depended on three factors:
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s s load, and bobbin depth. Two different levels (low and high) of each factor were chosen,
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s s and a single observation on flow was made for each combination of levels.
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a. The resulting data set consisted of how many observations?
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b. Is this an enumerative or analytic study? Explain your reasoning.
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ANS:
a. Number observations equal 22 2=8 s s s s s s


b. This could be called an analytic study because the data would be collected
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s s on an existing process. There is no sampling frame.
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PTS: 1

5. The accompanying data specific gravity values for various wood types used in construction .
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.41 .41 .42 .42. .42 .42 .42 .43 .44
.54 .55 .58 .62 .66 .66 .67 .68 .75
.31 .35 .36 .36 .37 .38 .40 .40 .40
.45 .46 .46 .47 .48 .48 .48 .51 .54

Construct a stem-and-leaf display using repeated stems and comment on any interesting features of the
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display.
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ANS:
One method of denoting the pairs of stems having equal values is to denote the stem by
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L, for ‗low‘ and the second stem by H, for ‗high‘.
s s s s s s Using this notation, the stem-and-leaf
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display would appear as follows:
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3L 1 stem:
tenths s s


3H 56678 leaf: hundredths
4L 000112222234
5L 144
5H 58
6L 2
6H 6678
7L
7H s s 5

The stem-and-leaf display on the previous page shows that .45 is a good representative value
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for the data. In addition, the display is not symmetric and appears to be positively
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skewed. s s The spread of the s s s s s s


data is s s s s


.75 - .31 = .44, which is .44/.45 = .978 or about 98% of the typical value of .45.
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This constitutes a reasonably large amount of s s s s ss s s s s s s


variation in the data.
s s The data value .75 is a possible outlier.
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PTS: 1

6. Temperature transducers of a certain type are shipped in batches of 50. A sample of 60
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s s batches was selected, and the number of transducers in each batch not conforming to
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s s design specifications was determined, resulting in the following data:
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0 4 2 1 1 3 4 1 2 3 2 2 8 4 5 1 3 1
1 3
2 1 2 1 3 2 0 5 3 3 1 3 2 4 7 0 2 3

, 4 0
5 0 2 1 0 6 4 2 1 6 0 3 3 3 6 1 2 3
3 2