**3. Stainless steels can be susceptible to stress corrosion cracking under certain conditions. A materials engineer is interested in determining the proportion of steel alloy failures that are due to stress corrosion cracking.**a. In the absence of preliminary data, how large a sample must be taken so as to be sure that a 98% confidence interval will specify the proportion to within ±0.05? Round up the answer to the nearest integer.b. In a sample of 200 failures, 30 of them were caused by stress corrosion cracking. Find a 98% confidence interval for the proportion of failures caused by stress corrosion cracking. Round the answers to three decimal places.c. Based on the data in part (b), estimate the sample size needed so that the 95% confidence interval will specify the proportion to within ±0.03. Round up the answer to the nearest integer.

Answered: Image /qna-images/answer/db832e4f-21dc-4652-b568-a99a91c26c2e.jpg

Answered: 3. Stainless steels can be susceptible…

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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Suppose we calculated the minimum sample size needed to create a C% confidence interval with a margin of error of 3.76 and a population standard deviation of 16.0 as n = 64. What was the confidence level, C? A. 86% B. 88% C. 92% D. 94%
1. The sample mean weights for two varieties of lettuce grown for 16 days in a controlled environment are 3.259 and 1.413 and the corresponding sample standard deviations are .400 and .220. If the sample sizes for the two varieties are 9 and 6 respectively, what would be the pair of hypotheses to test if the two varieties of lettuce have the same average weight? (Given: weight of each variety of lettuce is normally distributed). A. H0: μ1 ≠ μ2 vs H1: μ1 = μ2 B. H0: μ1 = μ2 vs H1: μ1 ≠ μ2 C.H0: μ1 > μ2 vs H1: μ1 ≤ μ2 D. H0: μ1 ≤ μ2 vs H1: μ1 > μ2 2. What is the best decision using critical value approach in problem 1? A. The computed test statistic falls in the critical region and we do not reject the null hypothesis. B. The computed test statistic does not fall in the critical region and we do not reject the null hypothesis. C. The computed test statistic falls in the critical region and we reject the null hypothesis. D. The computed test statistic does not fall…
3. A company wants to test a new energy drink. Two groups of samples were pooled out from the population. Find a 95% confidence interval for the difference between the two population means using the provided information below: Group Sample Size Standard Deviation Sample Mean (100-m running speed in seconds) Group A 45 125 10 Group B 60 140 8
3. If the mean of a sample of size 100 is 12 and the standard deviation is 2. Then 95% confidence limits are. а. 11.04, 12.96 b. 10.98, 13.02 c. 11.608, 12.392 d. 11.2, 12.8
1. A simple random sample of 21 people with early-onset dementia have the mean age at diagnosis of 52.3 years and the standard deviation of 6.5 years. Assume that ages at the diagnosis of dementia are normally distributed. We are to perform a hypotheses test to determine whether mean age at diagnosis of all people with early-onset dementia is different from 55 years. a. If one percent significance level is used then: i. RR = {t ≥ 2.528} ii. RR = {t ≤ −2.528} iii. RR={t≤−2.528}∪{t≥2.528} iv. RR = {t ≤ −2.845} v. RR = {t ≥ 2.845} vi. RR = {t ≤ −2.845}∪{t ≥ 2.845} b. At one percent significance level, we can conclude that mean age at diagnosis of all people with early-onset dementia is i. Is equal to 55 years 2. Is equal to 52.3 years 3. Is not equal to 52.3 years 4. Is not equal to 55 years
1. The National Center for Educational Statistics recently chose a random sample of 100 newly graduated college students and queried each one about the time it took to complete his or her degree. If the sample mean was 5 years with a sample variance of 4 years: a. Construct a 95 percent confidence interval estimate of the mean completion time of all newly graduated students. b. а. b. What is the interpretation of this confidence interval? If the sample increases, what will happen to the width of the confidence band (explain why you believe so). From past history, the average time for students to complete the degree is 4.8 years. Test the hypothesis at the level of 0.05 that it takes longer for students to complete the degree now. с.
1.
What does brand loyalty mean to consumers? According to a recent research report, 38% of consumers associate trust with brand loyalty. Complete parts (a) through (e) below. a. To conduct a follow-up study that would provide 95% confidence that the point estimate is correct to within ±0.04 of the population proportion, how large a sample size is required? A sample size of 566566 consumers is required. (Round up to the nearest integer.) b. To conduct a follow-up study that would provide 99% confidence that the point estimate is correct to within ±0.04 of the population proportion, how many people need to be sampled? A sample size of 978978 consumers is needed. (Round up to the nearest integer.) c. To conduct a follow-up study that would provide 95% confidence that the point estimate is correct to within ±0.02 of the population proportion, how large a sample size is required? A sample size of 22632263 consumers is…
What does brand loyalty mean to consumers? According to a recent research report, 38% of consumers associate trust with brand loyalty. Complete parts (a) through (e) below. a. To conduct a follow-up study that would provide 95% confidence that the point estimate is correct to within ±0.04 of the population proportion, how large a sample size is required? A sample size of ___ consumers is required.
1. Suppose a random sample of 32 National Football League players had an average weight of 252.5 pounds. Assume that the standard deviation for weight of all players in the league is 31 pounds. Determine the margin of error for a 99% confidence interval for this sample.
3
Assume that all grade-point averages are to be standardized on a scale between 0 and 6. How many grade-point averages must be obtained so that the sample mean is within 0.005 of the populationmean? Assume that a 99% confidence level is desired. If using the range rule of thumb, σ can be estimated as range4=6−04=1.5. Does the sample size seem practical?

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