Fluoride Exposure in Drinking Water Exercise 2.250 introduces a study showing that fluoride exposure might have long-termnegative consequences for the offspring of pregnant women. Part of the study examines the effect of adding fluoride to tap water onmean fluoride concentration in women. Summary statistics for fluoride concentration (measured in mg/L) for the two groups are givenin the table below.Tap waterFluoridatedNon-fluoridatedConclusion:Sample size141228Mean0.690.40St.Dev.0.420.27Find and interpret a 99% confidence interval for the mean increase in fluoride concentration for those with fluoridated tap water. LetGroup 1 represent those with fluoridated tap water and Group 2 represent those without fluoridated tap water.Confidence interval: ito i(round to three decimal places)

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Answered: Fluoride Exposure in Drinking Water…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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We are testing whether a particular program of low impact exercise can improve the cholesterol level of stroke patients. We enroll a group of stroke patients in our study, and after six weeks we measure their serum cholesterol level in mmol/L, resulting in the following data: 7.1 7.4 8.7 4.7 4.6 3.9 4.6 7.1 9.1 7.2 8.6 8.1 6.3 8 5.9 8.5 8.4 8 7.4 5.9 4.6 3.8 5.4 8.1 7.7 9.3 7.8 5.3 9 7.2 8.1 6.1 8.6 9.5 7.8 7.6 7.4 4.1 Construct a 92% confidence interval
Mercury is a persistent and dispersive environmental contaminant found in many ecosystems around the world. When released as an industrial by-product, it often finds its way into aquatic systems where it can have deleterious effects on various avian and aquatic species. The accompanying data on blood mercury concentration (µg/g) for adult females near contaminated rivers in a state was read from a graph in an article. 0.20 0.23 0.24 0.30 0.35 0.41 0.54 0.57 1.43 1.70 1.82 2.20 2.24 3.08 3.24 (a) Determine the values of the sample mean and sample median. Hint: xi = 18.55. (Round your answers to four decimal places.) x== Explain why they are different. The sample mean and sample median are never equal.They aren't different since the data is symmetric. There is heavy negative skewness in the data.There are an odd number of data values.There is heavy positive skewness in the data. (b) Determine the value of the 10% trimmed mean.…
A paper described a study that examined whether stress accelerates aging at a cellular level. The accompanying data on a measure of perceived stress (x) and telomere length (y) were read from a scatterplot that appeared in the paper. Telomere length is a measure of cell longevity. Perceivedstress Telomerelength Perceivedstress Telomerelength 5 1.06 20 2.1 6 1.1 20 1.14 6 1.18 20 0.98 7 1.02 21 1.14 10 1.9 21 2.14 11 1.46 21 1.66 12 1.02 22 1.78 13 1.58 22 2.26 14 1.3 22 0.9 14 0.94 23 2.42 15 1.98 24 1.1 15 1.62 24 1.66 15 1.7 25 2.14 17 1.14 26 1.26 17 1.06 27 1.98 17 1.78 27 2.34 18 1.38 28 1.34 18 1.62 29 2.22 19 1.94 33 0.94 (a) Compute the equation of the least-squares line. (Round your answer to four decimal places.) = (b) What is the value of r2? (Round your answer to four decimal places.)
In a previous practice assignment, you learned about a study in which volunteers (who were all around 30 years of age) from the Chicago area wore light sensors to measure their exposure to sunshine. It was found that those who experienced more daylight had lower body mass indexes (BMIs). The study was observational. It was not an experiment, so conclusions about cause and effect could not be made. Let's redesign the observational study described above into an experimental study.
Auto noise filters In a statement to a Senate Public WorksCommittee, a senior executive of Texaco, Inc., cited astudy on the effectiveness of auto filters on reducing noise. Because of concerns about performance, two types of fil-ters were studied, a standard silencer and a new device developed by the Associated Octel Company. Here are theboxplots from the data on noise reduction (in decibels) ofthe two filters. Type 1 = standard; Type 2 = Octel. ANOVA Table Source DFSum ofSquaresMeanSquare F-Ratio P-ValueType 1 6.31 6.31 0.7673 0.3874Error 33 271.47 8.22Total 34 2.77Means and Std DeviationsLevel n Mean StdDevStandard 18 81.5556 3.2166Octel 17 80.7059 2.43708a) What are the null and alternative hypotheses?b) What do you conclude from the ANOVA table?c) Do the assumptions for the test seem to be reasonable?d) Perform a two-sample pooled t-test of the difference.What P-value do you get? Show that the square of thet-statistic is the same (to rounding error) as the F-ratio.
1
If α = .05, is this difference statistically significant?
Research was conducted on the amount of oxygen runners could utilize during training, known as their VO2 max, and their finishing times for a 5K race to see if there was a significant relationship between these variables. The results for 8 runners were compiled and placed in the following table. VO2 Max (ml/kg/min) (x) 5K Finishing Time (min) (y) 16.28 34.66 20.55 37.41 18.62 34.11 15.78 37.36 18.12 37.56 39.49 23.7 26.88 28.72 43.39 20.69 Calculate the correlation coefficient. Round to three decimals. Find the equation of the regression line. Round each value to two decimals Preview Predict the time in the 5K for a runner whose VO, max is 30.12 ml/kg/min. Round your answer to two decimals Get Help: VIDEO
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Analysis of several plant-food preparations for potassium ion yielded the following data: Sample Percent K+ 1 6.02, 6.04, 5.88, 6.06, 5.82 2 7.48, 7.47, 7.29 3 3.90, 3.96, 4.16, 3.96 4 4.48, 4.65, 4.68, 4.42 5 5.29, 5.13, 5.14, 5.28, 5.20 The preparations were randomly drawn from the same population. a. Find the mean and standard deviation s for each sample b. Obtain the pooled value spooled c.Why is spooled a better estimate of s than the standard deviation from any one sample?
7.38 Food intake and weight gain. If we increase our food intake, we generally gain weight. Nutrition scientists can calculate the amount of weight gain that would be associated with a given increase in calories. In one study, 16 nonobese adults, aged 25 to 36 years, were fed 1000 calories per day in excess of the calories needed to maintain a stable body weight. The subjects maintained this diet for eight weeks, so they consumed a total of 56,000 extra calories.18 According to theory, 3500 extra calories will translate into a weight gain of 1 pound. Therefore, we expect each of these subjects to gain 56,000/3500 = 16 pounds (lb). Here are the weights before and after the eight-week period, expressed in kilograms (kg): WTGAIN Subject 1 2 3 Weight before 55.7 54.9 59.6 Weight after 4 5 6 7 8 62.3 74.2 75.6 70.7 53.3 61.7 58.8 66.0 66.2 79.0 82.3 74.3 59.3 Subject 9 10 11 12 13 14 15 Weight before 73.3 63.4 68.1 73.7 91.7 55.9 61.7 Weight after 79.1 66.0 73.4 76.9 93.1 63.0 68.2 W wr ore…

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