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 8.3, Problem 38E
A random sample of soil specimens was obtained, and the amount of organic matter (%) in the soil was determined for each specimen, resulting in the accompanying data (from “Engineering Properties of Soil,” Soil Science, 1998: 93–102).
The values of the sample mean, sample standard deviation, and (estimated) standard error of the mean are 2.481, 1.616, and .295, respectively. Does this data suggest that the true average percentage of organic matter in such soil is something other than 3%? Carry out a test of the appropriate hypotheses at significance level. 10. Would your conclusion be different if α = .05 had been used? [Note: A normal probability plot of the data shows an acceptable pattern in light of the reasonably large
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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
Question 4 of 4 (1 point) | Question Attempt: 2 of Unlimited
✓ 2
✓ 3
= 4
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…
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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- 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…arrow_forwardConduct the hypothesis test and provide the test statistic and the critical value, and state the conclusion. A person drilled a hole in a die and filled it with a lead weight, then proceeded to roll it 200 times. Here are the observed frequencies for the outcomes of 1, 2, 3, 4, 5, and 6, respectively: 28, 32, 46, 39, 29, 26. Use a 0.025 significance level to test the claim that the outcomes are not equally likely. Does it appear that the loaded die behaves differently than a fair die? Click here to view the chi-square distribution table. The test statistic is (Round to three decimal places as needed.) 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 1 0.001 0.004 0.016 2.706 3.841 5.024 6.635 2 0.010 0.020 0.051 0.103 0.211 4.605 5.991 7.378 9.210 7.879 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 0.484 0.711 1.064 7.779 9.488 11.143 13.277 14.860 5…arrow_forwardThe online clothing retailer e-Parel is conducting a study to estimate the average size of the orders placed by visitors to its website. The project manager desires a $60 bound on the error of estimation at 90% confidence. The population standard deviation is unknown, and a “best guess” of $175 is used as the planning value for σ. Use the Distributions tool to help you answer the questions that follow. 0123 Select a Distribution The z-value for a 90% confidence interval of the population mean is . In order to satisfy the requirement of a $60 bound on the error of estimation, a sample size no smaller than is needed.arrow_forward
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