8)A team of designers was given the task of reducing the defect rate in the manufacture of acertain printed circuit board. The team decided to reconfigure the cooling system. A total of 971boards were produced the week before the reconfiguration was implemented, and 253 of thesewere defective. A total of 845 boards were produced the week after reconfiguration, and 190 ofthese were defective.(a) Construct a 98% confidence interval for the decrease in the defective rate after thereconfiguration. Round the answers to three decimal places.(b) A quality control engineer claims that the reconfiguration has decreased theproportion of defective parts by more than 0.18. Does the confidence intervalcontradict this claim?9

Answered: Image /qna-images/answer/ade6d45d-875d-48ad-a59a-8789d13d87bf.jpg

Answered: 8)A team of designers was given the…

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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An apple farmer inspects a large random sample of his apples and finds that 20% contain excellent worms. He wants to charge his customers extra, and claims that the 90% confidence interval for the population pro- portion of apples that contain worms has a margin of error of at most 0.01. At least how many apples did the farmer inspect?
(c) An epidemiologist is worried about the ever increasing trend of malaria in a certain locality and wants to estimate the proportion of people infected in the peak malaria transmission period. If he takes a random sample of 150 people in that locality during the peak transmission period and finds that 60 of them are positive for malaria, find i. 99% confidence interval for the proportion of the whole infected people in that locality during the peak malaria transmission period.
Exercise 6.16 presents the results of a poll where 48% of 345 Americans who decide to not go to college do so because they cannot afford it.(a) Calculate a 90% confidence interval for the proportion of Americans who decide to not go to college because they cannot afford it, and interpret the interval in context. (b) Suppose we wanted the margin of error for the 90% confidence level to be about 1.5%. How large of a survey would you recommend?
(f) Suppose you and your business associates rent a store, get a bank loan to start up your business, and do a little research on the size of your sales district and the number of competing stores in the district. If x2 = 2.8, x3 = 250, x4 = 3.1, x5 = 7.3, and x6 = 2, use a computer to forecast x1 = annual net sales and find an 80% confidence interval for your forecast (if your software produces prediction intervals). (Use 2 decimal places.) forecast lower limit upper limit (g) Construct a new regression model with x4 as the response variable and x1, x2, x3, x5, and x6 as explanatory variables. (Use 2 decimal places for the intercept, 4 for x1, 5 for x3, and 3 otherwise.) x4 = + x1 + x2 + x3 + x5 + x6 Suppose an All Greens store in Sonoma, California, wants to estimate a range of advertising costs appropriate to its store. If it spends too little on advertising, it will not reach enough customers. However, it does not want to overspend on advertising for this type…
A certain article indicates that in a sample of 1,000 dog owners, 660 said that they take more pictures of their dog than of their significant others or friends, and 470 said that they are more likely to complain to their dog than to a friend. Suppose that it is reasonable to consider this sample as representative of the population of dog owners. (a) Construct a 90% confidence interval for the proportion of dog owners who take more pictures of their dog than of their significant others or friends. (Use a table or technology. Round your answers to three decimal places.) Interpret the interval. O We are 90% confident that the true proportion of dog owners who take more pictures of their dog than of their significant others or friends falls directly in the middle of this interval. There is a 90% chance that the true proportion of dog owners who take more pictures of their dog than of their significant others or friends falls within this interval. O We are 90% confident that the true…
A regional Internet service provider (ISP) is interested in whether a 15% discount on its price for its highest-speed service will notably impact customer retention. To answer this question, the ISP randomly chooses 75 of the 150 markets it serves to receive the 15% discount and keeps prices the same in the remaining 75 markets. After six months, the ISP observes the following: • For the markets receiving the discount, the average retention rate was 0.93 (i.e., 93%), with a standard deviation of 0.255. • For the markets not receiving the discount, the average retention rate was 0.88, with a standard deviation of 0.325. Using a 95% confidence interval, determine whether you can state with 95% confidence that the discount improved the six-month retention rate.
Mechanical components are being produced continuously. A quality control program for the mechanical components requires a close estimate of the proportion defective in production when all settings are correct. 1020 components are examined under these conditions, and 27 of the 1020 items are found to be defective. (a) Find a point estimate of the proportion defective. (b) Find a 95% two-sided confidence interval. (c) Find an upper limit giving 95% level of confidence that the true proportion defective is less than this limiting value. Use Excel in parts (b) and (c).OOnly a part needed.
Researchers want to test a new hand exercise plan for arthritis patients to see if they have improved flexibility. They recruited 110 patients with arthritis in their hands and randomly assigned them to one of two treatment groups: group i took their regular medicine and did the new hand exercises; and group 2 only took medicine. After one month, 42 of the 55 in group 1 improved in their flexibility, and 37 of the 55 in group 2 improved their flexibility. Based on the 95% confidence interval (-0.076, 0.258), is there convincing evidence of a difference in the proportion of patients like these who would show improvement in flexibility if they did the new hand exercises along with taking the medicine versus just taking the medicine? v to believe there va difference in the proportion of patients like these who would show improvement in flexibility if they did the new hand exercises along with taking the medicine versus just taking the medicine. Because v contained in the interval, there…
A random sample of 250 SCC students yields 79 full-timers and 171 part-timers. (a)Construct a 90% confidence interval for the overall proportion of full-time students at SCC.(b)The margin of error associated with the above c.i. is_____(c)How large a sample should be selected if we want the margin of error to be 2 percentage points?
A telephone service representative believes that the proportion of customers completely satisfied with their local telephone service is different between the South and the Northeast. The representative's belief is based on the results of a survey. The survey included a random sample of 700700 southern residents and 580580 northeastern residents. 49%49% of the southern residents and 42%42% of the northeastern residents reported that they were completely satisfied with their local telephone service. Find the 80%80% confidence interval for the difference in two proportions. Step 2 of 3: Find the value of the standard error. Round your answer to three decimal places.

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