Permeability of sandstone during weathering. Refer to the Geographical Analysis (Vol. 42, 2010) study of the decay properties of sandstone when exposed to the weather, Exercise 2.69 (p. 81). Recall that blocks of sandstone were cut into 300 equal-sized slices, and the slices were randomly divided into three groups of 100 slices each. Slices in Group A were not exposed to any type of weathering; slices in Group B were repeatedly sprayed with a 10% salt solution (to simulate wetting by driven rain) under temperate conditions; and, slices in Group C were soaked in a 10% salt solution and then dried (to simulate blocks of sandstone exposed during a wet winter and dried during a hot summer). All sandstone slices were then tested for permeability, measured in milliDarcies (mD). The data for the study (simulated) are saved in the accompanying file. Is it plausible to assume that the permeability measurements in any of the three experimental groups are approximately
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STATISTICS F/BUS.+ECON.-18WK. MYSTATLAB
- Suppose a researcher is interested inthe effectiveness in a new childhood exercise program implemented in a SRS of schools across a particular county. In order to test the hypothesis that the new program decreases BMI (Kg/m2), the researcher takes a SRS of children from schools where the program is employed and a SRS from schools that do not employ the program and compares the results. Assume the following table represents the SRSs of students and their BMIs. Student intervention group BMI (kg/m2) Student control group BMI (kg/m2) A 18.6 A 21.6 B 18.2 B 18.9 C 19.5 C 19.4 D 18.9 D 22.6 E 24.1 F 23.6 A) Assuming that all the necessary conditions are met (normality, independence, etc.) carry out the appropriate statistical test to determine if the new exercise program is effective. Use an alpha level of 0.05. Do not assume equal variances.B) Construct a 95% confidence interval about your estimate for the average difference in BMI between the groups.arrow_forward1. In the book Design and Analysis of Experiments, 8th edition (2012, John Wiley & Sons), the results of an experiment involving a storage battery used in the launching mechanism of a shoulder-fired ground-to-air missile were presented. Three material types can be used to make the battery plates. The objective is to design a battery that is relatively unaffected by the ambient temperature. The output response from the battery is effective life in hours. Three temperature levels are selected, and a factorial experiment with four replicates is run. The data are as follows: Table 11.(a) Test the appropriate hypotheses and draw conclusions using the analysis ether either firing temperature or furnace position affects the baked density of a carbon anode. The data are as follows: Table 12.(a) State the hypotheses of interest. (b) Test the hypotheses in part (a) using the analysis of variance with a = 0.05. What are your conclusions? (c) Analyze the residuals from this experiment. (d)…arrow_forwardA study was conducted to examine if children with autism spectrum disorder (ASD) had higher prenatal exposure to air pollution, specifically particulate matter < 2.5 g in diameter (PM2.5). Researchers obtained birth records of all children born in Los Angeles between 2000 and 2008 and linked these to the Department of Developmental Services records to determine if any of those subjects had been diagnosed with ASD or not. They used the birth addresses given in the birth records to determine the average daily PM2.5 for the third trimester for each child. The standard deviation for PM2.5 among ASD subjects was found to be 34.6 and for non-ASD subjects was 16.8. Assume PM2.5 is normally distributed. 4a. What was the study design? * Randomized Clinical Trial (RCT) * Case Report * Nested Case-Control Study * Case-Control Study * cross-sectional study Cohort Study 4B. What are the null and alternative hypotheses? 4c. What type of statistical test would you use to analyze the…arrow_forward
- The final test and exam averages for 20 randomly selected students taking a course in engineering statistics and a course in operations research are in Table E11-7. Assume that the final averages are jointly normally distributed.arrow_forwardFollowing are the protein contents measured in two types of species:Species 1: 0.72 1.12 0.81 0.89 0.72 0.81 1.01 0.75 0.83Species 2: 1.21 0.93 0.80 1.12 1.22 0.94 0.87 i) Assuming normality, test the hypothesis that the two species have the sameaverage protein contents by using 5-step hypothesis testing procedure at 5 %level of significance, and using the critical values approach.ii) Calculate the p-value of this test and make decision.iii) Write down the standard error of this test and calculate its numerical value ?arrow_forwardA sample of men and women who had passed their driver's test either the first time or the second time were surveyed, with the following results: Results of the driving testGender First time Second timeMen 126 211Women 135 178a) Do these data suggest that there is a relationship between gender and the passing of their driver’s test from which the present sample was drawn? Let alpha=.05arrow_forward
- Suppose that, as part of a research methods class, Bailey was asked to write a summary of a research paper on the topic of the effects of oil contamination in soil on seed germination rates. Identify the explanatory and the response variables.arrow_forwardReducing scrap of 4-foot planks of hardwood is an important factor in reducing cost at a wood-flooring manufacturing company. Accordingly, engineers at Lumberworks are investigating a potential new cutting method involving lateral sawing that may reduce the scrap rate. To examine its viability, samples of 600 and 500 planks, respectively, were examined under the old and new methods. Sixty-one of the 600 planks were scrapped under the old method, whereas 36 of the 500 planks were scrapped under the new method. (You may find it useful to reference the appropriate table: z table or t table)a. Construct the 99% confidence interval for the difference between the population scrap rates between the old and new methods, respectively. (Negative values should be indicated by a minus sign. Round intermediate calculations to at least 4 decimal places and final answers to 2 decimal places.)arrow_forwardResearchers interested in lead exposure due to car exhaust sampled the blood of 52 police officers subjected to constant inhalation of automobile exhaust fumes while working traffic enforcement in a primarily urban environment. The blood samples of these officers had an average lead concentration of 124.32 µg/l and an SD of 37.74 µg/l; a previous study of individuals from a nearby suburb, with no history of exposure, found an average blood level concentration of 35 µg/l. Write down the hypotheses that would be appropriate for testing if the police officers appear to have been exposed to a higher concentration of lead. Explicitly state and check all conditions necessary for inference on these data. Test the hypothesis that the downtown police officers have a higher lead exposure than the group in the previous study. Interpret your results in context. Based on your preceding result, without performing a calculation, would a 99% confidence interval for the average blood concentration…arrow_forward
- A snack food manufacturer estimates that the variance of the number of grams of carbohydrates in servings of its tortilla chips is 1.34. A dietician is asked to test this claim and finds that a random sample of 16 servings has a variance of 1.22. At α=0.05, is there enough evidence to reject the manufacturer's claim? Assume the population is normally distributed. Complete parts (a) through (e) below.arrow_forward(1) Conduct a hypothesis test, at the 5% level of significance, to determine whether ? is significant (2) What would be the growth of the plant if 4g of fertilizer and 7g of ater was given to it daily? (3) Carry out an F -test at the 1% significance level to determine whether the model is significantarrow_forwardA recent poll found that 664 out of 1026 randomly selected people in a particular country felt that colleges and universities with big sports programs placed too much emphasis on athletics over academics. Assuming the conditions for the CLT are met, use the accompanying Minitab output to complete parts a and b below. N Event Sample p 95% CI for p 1026 664 0.647173 (0.617934, 0.676413) Question content area bottom b. Suppose a sports blogger wrote an article claiming that a majority of adults from this country believe that colleges and universities with big sports programs place too much emphasis on athletics over academics. Does this confidence interval support the blogger's claim? Explain your reasoning. A. No, it is not a plausible claim because the confidence interval contains 50%. B. No, it is not a plausible claim because the confidence interval does not contain only values above 50%. C. Yes, it is a…arrow_forward
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