Statistics for Business and Economics (13th Edition)
13th Edition
ISBN: 9780134506593
Author: James T. McClave, P. George Benson, Terry Sincich
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 15, Problem 15.97ACI
Fluoride in drinking water. Many water treatment facilities supplement the natural fluoride concentration with hydrofluosilicic acid in order to reach a target concentration of fluoride in drinking water. Certain levels are thought to enhance dental health, but very high concentrations can be dangerous. Suppose that one such treatment plant targets .75 milligram per liter (mg/L) for their water. The plant tests 25 samples each day to determine whether the
- a. Set up the null and alternative hypotheses.
- b. Set up the test statistic and rejection region using α = .10.
- c. Explain the implication of a Type I error and a Type II error in the context of this application.
- d. Suppose that one day’s samples result in 18 values that exceed .75 mg/L. Conduct the test and state the appropriate conclusion in the context of this application.
- e. When it was suggested to the plant’s supervisor that a t-test should be used to conduct the daily test, she replied that the probability distribution of the fluoride concentrations was “heavily skewed to the right.” Show graphically what she meant by this and explain why this is a reason to prefer the sign test to the t-test.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Radon is a gas emitted from the ground that can collect in houses in buildings. At certain levels it can cause lung cancer. Radon concentrations are measured in picocuries per liter (pCi/L). A radon level of 4 pCi/L is considered “acceptable” Radon levels in a house vary from week to week. In one house, a sample of 6 weeks had the following readings for radon level (in pCi/L):
1.9 2.8 3.9 3.9 4.2 5.7
Find the variance and standard deviation (definitional formula). Show your work using a table.
For each of the questions 1-4, answer the following (a-h are steps in a Hypothesis Test, see page 376 of your ebook). For steps f and g do both the p-value
method and the critical value method:
a) Claim in English:
b) Claim in Symbolic Form:
c) Null and Alternate Hypothesis:
d) Significance Level:
e) Test Statistic:
f) Find Values:
g) Make a Decision:
h) Restate the Decision in Nontechnical Terms:
i) If this is a statistically significant result, is it also a practically significant result?
Periodically, the county Water Department tests the drinking water of homeowners for contaminants
such as lead and copper. The lead and copper levels in water specimens collected in 1998 for a
sample of 10 residents of a subdevelopement of the county are shown below.
lead (g/L) copper (mg/L)
2.9
0.2
5.1
4.2
5.5
1.2
0.3
1.3
4.9
1.7
0.133
0.774
0.214
0.671
0.444
0.234
0.357
0.761
0.176
0.888
(a) Construct a 99% confidence interval for the mean lead level in water specimans of the
subdevelopment.
OSASO
(b) Construct a 99% confidence interval for the mean copper level in water specimans of the
subdevelopment.
≤H≤
Chapter 15 Solutions
Statistics for Business and Economics (13th Edition)
Ch. 15.2 - Under what circumstances is the sign test...Ch. 15.2 - What is the probability that a randomly selected...Ch. 15.2 - Use Table I of Appendix D to calculate the...Ch. 15.2 - Consider the following sample of 10 measurements....Ch. 15.2 - Suppose you wish to conduct a test of the research...Ch. 15.2 - Accidents at construction sites. Refer to the...Ch. 15.2 - Salaries of experienced MBA graduates. According...Ch. 15.2 - Caffeine in Starbucks coffee. Researchers at the...Ch. 15.2 - Short-sale stock returns. The Securities and...Ch. 15.2 - Lobster trap placement. Refer to the Bulletin of...
Ch. 15.2 - Repair and replacement costs of water pipes. Refer...Ch. 15.2 - Performance of stock screeners. Refer to Exercise...Ch. 15.2 - Radon exposure in Egyptian tombs. Refer to the...Ch. 15.2 - Prob. 15.14ACICh. 15.3 - Prob. 15.15LMCh. 15.3 - Specify the test statistic and the rejection...Ch. 15.3 - Prob. 15.17LMCh. 15.3 - Prob. 15.18LMCh. 15.3 - Prob. 15.19ACBCh. 15.3 - Prob. 15.21ACBCh. 15.3 - Prob. 15.22ACBCh. 15.3 - The X-Factor in golf performance. Many golf...Ch. 15.3 - Prob. 15.24ACICh. 15.3 - Prob. 15.25ACICh. 15.3 - Prob. 15.26ACICh. 15.3 - Does rudeness really matter in the workplace?...Ch. 15.3 - Prob. 15.28ACICh. 15.4 - Prob. 15.29LMCh. 15.4 - Prob. 15.30LMCh. 15.4 - Prob. 15.31LMCh. 15.4 - Prob. 15.32LMCh. 15.4 - Twinned drill holes. Refer to the Exploration and...Ch. 15.4 - Prob. 15.34ACBCh. 15.4 - Prob. 15.35ACBCh. 15.4 - Prob. 15.36ACBCh. 15.4 - Prob. 15.37ACBCh. 15.4 - Prob. 15.38ACICh. 15.4 - Prob. 15.39ACICh. 15.4 - Prob. 15.40ACICh. 15.4 - Prob. 15.41ACICh. 15.4 - Prob. 15.42ACICh. 15.5 - Under what circumstances does the 2 distribution...Ch. 15.5 - Data were collected from three populations, A, B....Ch. 15.5 - Prob. 15.45LMCh. 15.5 - Prob. 15.46ACBCh. 15.5 - Prob. 15.47ACBCh. 15.5 - Prob. 15.48ACBCh. 15.5 - Prob. 15.49ACBCh. 15.5 - Prob. 15.50ACICh. 15.5 - Public defenders salaries. Random samples of seven...Ch. 15.5 - Prob. 15.52ACICh. 15.5 - Prob. 15.53ACICh. 15.6 - Prob. 15.54LMCh. 15.6 - Prob. 15.55LMCh. 15.6 - Prob. 15.56LMCh. 15.6 - Prob. 15.57ACBCh. 15.6 - Condit ions impeding farm production. A review of...Ch. 15.6 - Peer mentor training at a firm. Refer to the...Ch. 15.6 - Prob. 15.60ACBCh. 15.6 - Prob. 15.61ACICh. 15.6 - Prob. 15.62ACICh. 15.6 - Prob. 15.63ACICh. 15.6 - Prob. 15.64ACICh. 15.6 - Prob. 15.65ACICh. 15.7 - Prob. 15.66LMCh. 15.7 - Prob. 15.67LMCh. 15.7 - The following sample data were collected on...Ch. 15.7 - Compute Spearman s rank correlation coefficient...Ch. 15.7 - Charisma of top-level leaders. Refer to the...Ch. 15.7 - Prob. 15.71ACBCh. 15.7 - Prob. 15.72ACBCh. 15.7 - Prob. 15.73ACBCh. 15.7 - Prob. 15.74ACICh. 15.7 - Prob. 15.75ACICh. 15.7 - Prob. 15.76ACICh. 15.7 - Prob. 15.77ACICh. 15.7 - Sweetness of orange juice Refer to the orange...Ch. 15.7 - Americas most reputable companies. Forbes magazine...Ch. 15 - The data for three independent random samples are...Ch. 15 - Prob. 15.81LMCh. 15 - Two independent random samples produced the...Ch. 15 - Prob. 15.83LMCh. 15 - Prob. 15.84ACBCh. 15 - Prob. 15.85ACBCh. 15 - Office rental growth rates Real estate market...Ch. 15 - RIF plan to fire older employees. Reducing the...Ch. 15 - Prob. 15.88ACBCh. 15 - Wine-tasting experiment. Two expert wine tasters...Ch. 15 - Employee suggestion system. An employee suggestion...Ch. 15 - Prob. 15.91ACICh. 15 - Prob. 15.92ACICh. 15 - Prob. 15.93ACICh. 15 - Prob. 15.94ACICh. 15 - Cooling method for gas turbines. Refer to the...Ch. 15 - Flexible working hours program. A job-scheduling...Ch. 15 - Fluoride in drinking water. Many water treatment...Ch. 15 - Does fatigue lead to more defectives? A...Ch. 15 - Prob. 15.99ACICh. 15 - Prob. 15.100ACICh. 15 - Prob. 15.101ACICh. 15 - Groundwater contamination of wells. Methyl...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.Similar questions
- Find the mean hourly cost when the cell phone described above is used for 240 minutes.arrow_forwardA sociologist wants to determine if the life expectancy of people in Africa is less than the life expectancy of people in Asia. The data obtained is shown in the table below. Africa Asia = 63.3 yr. 1 X,=65.2 yr. 2 o, = 9.1 yr. = 7.3 yr. n1 = 120 = 150arrow_forwardPeriodically, the county Water Department tests the drinking water of homeowners for contaminants such as lead and copper. The lead and copper levels in water specimens collected in 1998 for a sample of 10 residents of a subdevelopement of the county are shown below. lead (μμg/L) copper (mg/L) 4.4 0.643 2.4 0.57 1.5 0.46 2.6 0.895 5.9 0.2 3.4 0.54 3.8 0.245 1.6 0.583 5.7 0.769 1.7 0.215 (a) Construct a 9999% confidence interval for the mean lead level in water specimans of the subdevelopment. ≤μ≤arrow_forward
- Periodically, the county Water Department tests the drinking water of homeowners for contaminants such as lead and copper. The lead and copper levels in water specimens collected in 1998 for a sample of 10 residents of a subdevelopement of the county are shown below. lead (g/L) 2.9 0.2 5.1 4.2 5.5 1.2 0.133 0.774 0.214 0.671 0.444 0.234 0.357 0.761 0.176 0.888 (a) Construct a 99% confidence interval for the mean lead level in water specimans of the subdevelopment. OSMOSO copper (mg/L) 0.3 1.3 4.9 1.7 (b) Construct a 99% confidence interval for the mean copper level in water specimans of the subdevelopment. OSHSOarrow_forwardWhat percentage of women that did not receive the treatment showed hair growth of 1-2 inches? Answer: Blank 1: Blank 2: Blank 3: Blank 4: Chp -> & #3 $4 9. 8 6. 3 4. y earrow_forwardSamples are collected from the River X and pH values are observed. 9 different pH values are listed in table 3. Table 3 Concentrations 4.2 Draw box plot and find a. Bowley's coefficient of skewness b. Karl Pearson's coefficient of skewness c. Third moment 3.8 6.0 3.5 8.1 4.9 4.1 3.2 4.0arrow_forward
- Air samples for worker's exposure to oil mist were found to indicate the following levels in Table 1. Calculate TWA. Table 1 Sample Measured Amount Time of Sample 3 mg/m 28 mg/m Sample 1 2 hours Sample 2 6 hours (a) 6.57 mg/m³ (b) 6.75 mg/m' (c) 54 mg/m (d) 31 mg/marrow_forwardRadon is a colorless, odorless gas that is naturally released by rocks and soils and may concentrate in tightly closed houses. Since radon is slightly radioactive, there is some concern that it may be a health hazard. Radon detectors are sold to homeowners worried about this risk, but the detectors may be inaccurate. University researchers placed 30 radon detectors in a chamber where they were exposed to 105 picocuries per liter (pCi/l) of radon over 3 days. The sample average reading from the 30 radon detectors was 102.87 pCi/ and the sample standard deviation was 4.9 pCiA. Are the researchers able to conclude at the 5% significance level that the average reading differs from the true value of 105? To test: Ho u vs. Ha Test Statistic (Round to three decimals) (Click to select) p-value (Round to three decimals) Conclusion: At a = evidence to conclude that the Click to select) pCiA. KClick to select) since p-value (Click to select) M a. We have KClick to select) V reading (Click to…arrow_forwardA new purification unit is installed in a chemical process. Before its installation, a random sample yielded the following data about the percentage of impurity: x1 = 9.85 , S12 = 81.73 , and n1 = 8 . After installation, a random sample resulted in x2 = 8.08 , S2 = 78.46 , and n2 = 10 .arrow_forward
- Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 45 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 mg/kg (milliliters plasma per kilogram body weight). Assume that = 7.50 ml/kg for the distribution of blood plasma. a. Find a 95% confidence interval for the population mean blood plasma volume in male firefighters. b. What is the margin of error?arrow_forwardTrace metals in drinking water affect the flavor and an unusually high concentration can pose a health hazard. Ten pairs of data were taken measuring zinc concentration in bottom water and surface water. Bottom 0.430 0.266 0.567 0.531 0.707 0.716 0.651 0.589 0.469 0.723 Surface 0.415 0.238 0.390 0.410 0.605 0.609 0.632 0.523 0.411 0.612 With the help of Mathematics and R Studio: Does the data suggest that the true average concentration in the bottom water is different than that of surface water? You can assume that the conditions for inference are met.arrow_forwardTo estimate the size of a new dam, you have to determine the total volume of water that flows down a river in years’ time. You have available the following long term average data for the river: Determine the estimated volume of the river. Assume 30 days per month.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
College Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning
Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill
College Algebra (MindTap Course List)
Algebra
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:Cengage Learning
Glencoe Algebra 1, Student Edition, 9780079039897...
Algebra
ISBN:9780079039897
Author:Carter
Publisher:McGraw Hill
Hypothesis Testing using Confidence Interval Approach; Author: BUM2413 Applied Statistics UMP;https://www.youtube.com/watch?v=Hq1l3e9pLyY;License: Standard YouTube License, CC-BY
Hypothesis Testing - Difference of Two Means - Student's -Distribution & Normal Distribution; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=UcZwyzwWU7o;License: Standard Youtube License