Answered: An experiment to compare the tension…

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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Transcribed Image Text:QUESTION 1 An experiment to compare the tension bond strength of polymer latex modified mortar (Portland cement mortar to which polymer latex emulsions have been added during mixing) to that of unmodified mortar resulted in ₁ = 18.13 kgf/cm2 for the modified mortar (n₁ = 38) and ₂ = 16.81 kgf/cm2 for the unmodified mortar (n₂ = 31). Let μ₁ and ₂ be the true average tension bond strengths for the modified and unmodified mortars, respectively. Assume that the bond strength distributions are both normal. Assuming that σ₁ = 1.7 and σ₂ = 1.3, construct a 99% confidence interval for the difference in means. What is the lower bound of this interval? Round to two decimal places as necessary. QUESTION 2 Many freeways have service (or logo) signs that give information on attractions, camping, lodging, food, and gas services prior to off-ramps. These signs typically do not provide information on distances. An article reported that in one investigation, six sites along interstate highways where service signs are posted were selected. For each site, crash data was obtained for a three-year period before distance information was added to the service signs and for a one-year period afterward. The number of crashes per year before and after the sign changes were as follows. Before 15 26 65 119 61 64 After 16 24 43 81 77 73 The article included the statement "A paired t test was performed to determine whether there was any change in the mean number of crashes before and after the addition of distance information on the signs." Carry out such a test. What is the value of the test statistic for this test? Round to three decimal places as necessary. QUESTION 3 Many freeways have service (or logo) signs that give information on attractions, camping, lodging, food, and gas services prior to off-ramps. These signs typically do not provide information on distances. An article reported that in one investigation, six sites along interstate highways where service signs are posted were selected. For each site, crash data was obtained for a three-year period before distance information was added to the service signs and for a one-year period afterward. The number of crashes per year before and after the sign changes were as follows. Before 14 26 68 119 62 62 After 15 24 45 82 77 71 The article included the statement "A paired t test was performed to determine whether there was any change in the mean number of crashes before and after the addition of distance information on the signs." Carry out such a test. What is the value of the test statistic for this test? Round to three decimal places as necessary. QUESTION 4 The degenerative disease osteoarthritis most frequently affects weight-bearing joints such as the knee. An article presented the following summary data on stance duration (ms) for samples of both older and younger adults. Age Sample Size Sample Mean Sample SD Older 8.04 76.9 117 75 Younger We want to test whether the mean stance duration for the older group is less than the mean stance duration for the younger group. What is the p-value for this test? Round to three decimal places as necessary. 28 19 QUESTION 5 The degenerative disease osteoarthritis most frequently affects weight-bearing joints such as the knee. An article presented the following summary data on stance duration (ms) for samples of both older and younger adults. Age Sample Size Sample Mean Sample SD Older 8.06 77.2 119 75 Younger We want to test whether the mean stance duration for the older group is less than the mean stance duration for the younger group. What is the p-value for this test? Round to three decimal places as necessary. 26 16

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