Student Solutions Manual for Devore's Probability and Statistics for Engineering and the Sciences, 9th
9th Edition
ISBN: 9798214004020
Author: Jay L. Devore
Publisher: Cengage Learning US
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Chapter 8, Problem 61SE
Contamination of mine soils in China is a serious environmental problem. The article “Heavy Metal Contamination in Soils and Phytoaccumulation in a Manganese Mine Wasteland, South China” (Air, Soil, and Water Res., 2008: 31–41) reported that, for a sample of 3 soil specimens from a certain restored mining area, the sample mean concentration of Total Cu was 45.31 mg/kg with a corresponding (estimated) standard error of the mean of 5.26. It was also stated that the China background value for this concentration was 20. The results of various statistical tests described in the article were predicated on assuming normality.
- a. Does the data provide strong evidence for concluding that the true average concentration in the sampled region exceeds the stated background value? Carry out a test at significance level .01. Does the result surprise you? Explain.
- b. Referring back to the test of (a), how likely is it that the P-value would be at least .01 when the true average concentration is 50 and the true standard deviation of concentration is 10?
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very time you conduct a hypothesis test, there are four possible outcomes of your decision to reject or not reject the null hypothesis: (1) You don’t reject the null hypothesis when it is true, (2) you reject the null hypothesis when it is true, (3) you don’t reject the null hypothesis when it is false, and (4) you reject the null hypothesis when it is false.
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Ch 6 Sec 4 Homework
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Stress at work: In a poll conducted by the General Social Survey, 81% of respondents said that their jobs were sometimes or always stressful. Two hundred
workers are chosen at random. Use the TI-84 Plus calculator as needed. Round your answer to at least four decimal places.
(a) Approximate the probability that 155 or fewer workers find their jobs stressful.
(b) Approximate the probability that more than 145 workers find their jobs stressful.
(c) Approximate the probability that the number of workers who find their jobs stressful is between 154 and 172 inclusive.
Part 1 of 3
The probability that 155 or fewer workers find their jobs stressful is 0.1207
Part 2 of 3
bility that more than 145 workers find their jobs…
A case-control (or retrospective) study was conducted to investigate a relationship between the colors of helmets worn by motorcycle drivers and whether they are injured or killed in a crash. Results are given in the accompanying table. Using a 0.01
significance level, test the claim that injuries are independent of helmet color.
Color of Helmet
Black
White
Yellow
Red
Blue
Controls (not injured)
499
373
32
159
79
Cases (injured
221
108
8
66
38
or killed)
Click here to view the chi-square distribution table.
Chi-square distribution table
Area to the Right of the Critical Value
Degrees of
Freedom
0.995
0.99
0.975
0.95
0.90
0.10
0.05
0.025
0.01
0.005
C. Ho: Injuries and neimet color are dependent
H₁: Injuries and helmet color are independent
D. Ho: Whether a crash occurs and helmet color are dependent
1
0.001
0.004
0.016
2.706
3.841
5.024
6.635
7.879
2
0.010
0.020
0.051
0.103
0.211
4.605
5.991
7.378
9.210
10.597
3
0.072
0.115
0.216
0.352
0.584
6.251
7.815
9.348
11.345
12.838
4
0.207
0.297…
Chapter 8 Solutions
Student Solutions Manual for Devore's Probability and Statistics for Engineering and the Sciences, 9th
Ch. 8.1 - For each of the following assertions, state...Ch. 8.1 - For the following pairs of assertions, indicate...Ch. 8.1 - For which of the given P-values would the null...Ch. 8.1 - Pairs of P-values and significance levels, , are...Ch. 8.1 - To determine whether the pipe welds in a nuclear...Ch. 8.1 - Let denote the true average radioactivity level...Ch. 8.1 - Before agreeing to purchase a large order of...Ch. 8.1 - Many older homes have electrical systems that use...Ch. 8.1 - Water samples are taken from water used for...Ch. 8.1 - A regular type of laminate is currently being used...
Ch. 8.1 - Prob. 11ECh. 8.1 - A mixture of pulverized fuel ash and Portland...Ch. 8.1 - The calibration of a scale is to be checked by...Ch. 8.1 - A new design for the braking system on a certain...Ch. 8.2 - Let denote the true average reaction time to a...Ch. 8.2 - Newly purchased tires of a particular type are...Ch. 8.2 - Answer the following questions for the tire...Ch. 8.2 - Reconsider the paint-drying situation of Example...Ch. 8.2 - The melting point of each of 16 samples of a...Ch. 8.2 - Lightbulbs of a certain type are advertised as...Ch. 8.2 - The desired percentage of SiO2 in a certain type...Ch. 8.2 - To obtain information on the corrosion-resistance...Ch. 8.2 - Automatic identification of the boundaries of...Ch. 8.2 - Unlike most packaged food products, alcohol...Ch. 8.2 - Body armor provides critical protection for law...Ch. 8.2 - Prob. 26ECh. 8.2 - Show that for any 0, when the population...Ch. 8.2 - For a fixed alternative value , show that () 0 as...Ch. 8.3 - The true average diameter of ball bearings of a...Ch. 8.3 - A sample of n sludge specimens is selected and the...Ch. 8.3 - The paint used to make lines on roads must reflect...Ch. 8.3 - The relative conductivity of a semiconductor...Ch. 8.3 - The article The Foremans View of Quality Control...Ch. 8.3 - The following observations are on stopping...Ch. 8.3 - The article Uncertainty Estimation in Railway...Ch. 8.3 - Have you ever been frustrated because you could...Ch. 8.3 - The accompanying data on cube compressive strength...Ch. 8.3 - A random sample of soil specimens was obtained,...Ch. 8.3 - Reconsider the accompanying sample data on expense...Ch. 8.3 - Polymer composite materials have gained popularity...Ch. 8.3 - A spectrophotometer used for measuring CO...Ch. 8.4 - Prob. 42ECh. 8.4 - Prob. 43ECh. 8.4 - A manufacturer of nickel-hydrogen batteries...Ch. 8.4 - A random sample of 150 recent donations at a...Ch. 8.4 - It is known that roughly 2/3 of all human beings...Ch. 8.4 - The article Effects of Bottle Closure Type on...Ch. 8.4 - With domestic sources of building supplies running...Ch. 8.4 - A plan for an executive travelers club has been...Ch. 8.4 - Each of a group of 20 intermediate tennis players...Ch. 8.4 - A manufacturer of plumbing fixtures has developed...Ch. 8.4 - In a sample of 171 students at an Australian...Ch. 8.5 - Reconsider the paint-drying problem discussed in...Ch. 8.5 - Consider the large-sample level .01 test in...Ch. 8.5 - Consider carrying out m tests of hypotheses based...Ch. 8.5 - Prob. 56ECh. 8 - A sample of 50 lenses used in eyeglasses yields a...Ch. 8 - In Exercise 57, suppose the experimenter had...Ch. 8 - It is specified that a certain type of iron should...Ch. 8 - One method for straightening wire before coiling...Ch. 8 - Contamination of mine soils in China is a serious...Ch. 8 - The article Orchard Floor Management Utilizing...Ch. 8 - The article Caffeine Knowledge, Attitudes, and...Ch. 8 - Annual holdings turnover for a mutual fund is the...Ch. 8 - The true average breaking strength of ceramic...Ch. 8 - Prob. 66SECh. 8 - The incidence of a certain type of chromosome...Ch. 8 - Prob. 68SECh. 8 - Prob. 69SECh. 8 - The Dec. 30, 2009. the New York Times reported...Ch. 8 - When X1, X2,, Xn are independent Poisson...Ch. 8 - An article in the Nov. 11, 2005, issue of the San...Ch. 8 - Prob. 73SECh. 8 - The article Analysis of Reserve and Regular...Ch. 8 - Prob. 75SECh. 8 - Chapter 7 presented a CI for the variance 2 of a...Ch. 8 - Prob. 77SECh. 8 - When the population distribution is normal and n...Ch. 8 - Let X1, X2, Xn be a random sample from an...Ch. 8 - Because of variability in the manufacturing...
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