Concept explainers
The article “Flexure of Concrete Beams Reinforced with Advanced Composite Orthogrids” (J. of Aerospace Engr., 1997: 7–15) gave the accompanying data on ultimate load (kN) for two different types of beams. Sample Sample Sample Type Size Mean SD Fiberglass grid 26 33.4 2.2 Commercial 26 42.8 4.3 carbon grid
Type | Sample Mean | Sample SD | |
Fiberglass grid | 26 | 33.4 | 2.2 |
Commercial | 26 | 42.8 | 4.3 |
carbon grid |
a. Assuming that the underlying distributions are normal, calculate and interpret a 99% CI for the difference between true average load for the fiberglass beams and that for the carbon beams.
b. Does the upper limit of the interval you calculated in part (a) give a 99% upper confidence bound for the difference between the two μ’s? If not, calculate such a bound. Does it strongly suggest that true average load for the carbon beams is more than that for the fiberglass beams? Explain.
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Chapter 9 Solutions
Student Solutions Manual for Devore's Probability and Statistics for Engineering and the Sciences, 9th
- Look at the attached images. There is the normality test and the Mann Whitney test for the two groups of INR and PCV (PCV1/a, PCV2/b , INR1/a, INR2/b). Interpret the data using both tests and explain why there may or may not be differences between the two cohorts.arrow_forwardThe article “Arsenic and Mercury in Lake Whitefish and Burbot Near the Abandoned Giant Mine on Great Slave Lake” (P. Cott, B. Zajdlik, et al., Journal of Great Lakes Research, 2016:223–232) presents measurements of arsenic concentrations in fish found in Northern Canada. a) In a sample of 8 whitefish caught in Yellowknife Bay, the mean arsenic concentration in the liver was 0.32 mg/kg, with a standard deviation of 0.05 mg/kg. Find a 95% confidence interval for the concentration in whitefish found in Yellowknife Bay. b) In a sample of 8 whitefish caught in Baker Pond, the mean arsenic concentration in the liver was 0.55 mg/kg, with a standard deviation of 0.36 mg/kg. Should the Student’s t distribution be used to find a 95% confidence interval for the concentration in whitefish found in Baker Pond? If so, find the confidence interval. If not, explain why not.arrow_forwardA recent Nielsen analysis found that the typical U.S. smartphone user is spending an average of 220 minutes per day using apps. We speculate that the average time spent using apps for Generation X smartphone users (aged 41-56 years) is less than the national average. The hypotheses are Ho: H = 220 minutes versus Ha: µ < 220 minutes. Summary results from R are provided. Summary Statistics Std. Dev (s) Mean Sample Size (n) 205 minutes 63.25 minutes 31arrow_forward
- (1) Two rubber compounds were tested for tensile strength and the fol- lowing values were found A : 32,30,33, 32, 29, 34, 32 B: 33,35, 36, 37,35, 34 Under the assumption that the two populations are normally distributed, test the hypothesis that the average tensile strength of the two rubber compounds is different using significance level a = 0.01 and a = 0.05.arrow_forwardThe article “Arsenic and Mercury in Lake Whitefish and Burbot Near the Abandoned Giant Mine on Great Slave Lake” (P. Cott, B. Zajdlik, et al., Journal of Great Lakes Research, 2016:223–232) presents measurements of arsenic concentrations in fish found in Northern Canada. In a sample of 8 whitefish caught in Yellowknife Bay, the mean arsenic concentration in the liver was 0.32 mg/kg, with a standard deviation of 0.05 mg/kg. Can you conclude that the mean arsenic concentration in whitefish in Yellowknife Bay is greater than 0.3 mg/kg?arrow_forwardBlood cocaine concentration (mg/L) was determinedboth for a sample of individuals who had died fromcocaine-induced excited delirium (ED) and for a sampleof those who had died from a cocaine overdose withoutexcited delirium; survival time for people in bothgroups was at most 6 hours. The accompanying datawas read from a comparative boxplot in the article“Fatal Excited Delirium Following Cocaine Use” (J.of Forensic Sciences, 1997: 25–31). ED 0 0 0 0 .1 .1 .1 .1 .2 .2 .3 .3.3 .4 .5 .7 .8 1.0 1.5 2.7 2.83.5 4.0 8.9 9.2 11.7 21.0Non-ED 0 0 0 0 0 .1 .1 .1 .1 .2 .2 .2.3 .3 .3 .4 .5 .5 .6 .8 .9 1.01.2 1.4 1.5 1.7 2.0 3.2 3.5 4.14.3 4.8 5.0 5.6 5.9 6.0 6.4 7.98.3 8.7 9.1 9.6 9.9 11.0 11.512.2 12.7 14.0 16.6 17.8 a. Determine the medians, fourths, and fourth spreadsfor the two samples.b. Are there any outliers in either sample? Any extremeoutliers?c. Construct a comparative boxplot, and use it as abasis for comparing and contrasting the ED andnon-ED samples.arrow_forward
- The amount of chlorine in 100 cm3 water taken from a water tank was measured, the average was 2.15 mg was found. The expert claims that the amount of chlorine in the water is greater than that measured. For this reason, 100 households were randomly selected, with an average chlorine content of 2.55mg and a variance of 0.49 mg. According to this data, find the account value z. 13 - O A) 8,15 O B) 5,71 O C) -5,71 O D) -8, 15 O E) 0.54arrow_forwardThe material of the plate on which our food is served might affect how much we eat (Williamson, Block, and Keller, 2016). Researchers gave 8 participant 2 donuts on paper plates and 8 participants 2 donuts on reusable plastic plates. They measured the grams of wasted food on each type of plate and analyzed the data using the SPSS printout below. Use Use α = .05 2tail to evaluate the statistic **Attached are the images** a. State the hypotheses b. Show how the t was calculated using the values from the SPSS printout. c. What is Cohen’s d? d. Show how the 95% confidence interval was calculated. e. State the conclusion in APA format.arrow_forwardThe article "Withdrawal Strength of Threaded Nails" (D. Rammer, S. Winistorfer, and D. Bender, Journal of Structural Engineering, 2001:442–449) describes an experiment comparing the withdrawal strengths for several types of nails. The data presented in the following table are consistent with means and standard deviations reported in the article for three types of nails: annularly threaded, helically threaded, and smooth shank. All nails had diameters within 0.1 mm of each other, and all were driven into the same type of lumber. Nail Withdrawal Strength (N/mm) Type Annularly 36.57 29.67 43.38 26.94 12.03 21.66 41.79 31.50 35.84 40.81 threaded Helically 14.66 24.22 23.83 21.80 27.22 38.25 28.15 36.35 23.89 28.44 threaded Smooth 12.61 25.71 17.69 24.69 26.48 19.35 28.60 42.17 25.11 19.98 shank Construct an ANOVA table. You may give a range for the P-value. Can you conclude that the mean withdrawal strength is different for different nail types? a. b.arrow_forward
- 5 c.)arrow_forwardA researcher was interested in whether there are differences in body image concerns between competitive vs. non-competitive athletes. Based on the forest plot below, what is your statistical conclusion? Difference in body image concerns between competitive and non- competitive athletes OA) Reject Ho Study Arroyo et al. (2008) Asci (2004) Benau et al., (2020) Di Bartolo & Shaffer (2002) Di Nucci et al, (1994) Filaire et al., (2007) Furnham et al, (1994) Hoag (2012) lacolino et al., (2017) Loosemore et al., (1989) Reinking & Alexander (2005) Robinson & Ferraro (2004) Souilliard et al., (2021) Souilliard et al., (2019) Warren et al, (1990) Wiggins & Moode (2000) Indicates lower levels of body image concerns among competitive athletes -2-1 C) Fail to Reject Ho HH Hedges g [95% CI) -0.54 (-1.08,-0.01] -0.26 [-0.40,-0.12] -0.28 [-0.53,-0.03] -0.69 (-0.97,-0.41] -1.01 [-1.52,-0.49] 2.29 [1.52, 3.06) -0.69 [-1.29,-0.09) 0.35 [0.12, 0.58]) -0.33 [-0.61,-0.05) 0.02 [-0.63, 0.67] -0.42 (-0.75,…arrow_forwardAn article about “Relative Controllability of Dissimilar Cars” reported a study in which 14 subjects were asked to parallel-park two cars having very different wheel bases and turning diameter. The time (in seconds) for each subject was recorded and found that the sample mean and sample variance of the difference were 1.21 seconds and 160.7824, respectively. The researcher claims that the population mean difference of time taken is (4.79,7.21) seconds. With what level of confidence can this statement be made?arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill