A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims "graded 200" on the sidewall of the tire. A random sample of n= 23 indicates a sample mean tread wear index of 189.9 and a sample standard deviation of 27.1. Complete parts (a) through (c). a. Assuming that the population of tread wear indexes is normally distributed, construct a 99% confidence interval estimate of the population mean tread wear index for tires produced by this manufacturer under this brand name. 173.97 Sus 205.83 (Round to two decimal places as needed.) b. Do you think that the consumer organization should accuse the manufacturer of producing tires that do not meet the perfomance information on the sidewall of the tire? Explain. O A. Yes, because a grade of 200 is not in the interval. O B. Yes, because a grade of 200 is in the interval. C. No, because a grade of 200 is in the interval. O D. No, because a grade of 200 is not in the interval. C. Explain why an observed tread wear index of 207 for a particular tire is not unusual, even though it is outside the confidence interval developed in (a). O A. It is not unusual because it is only 0.63 standard deviations above the sample mean. O B. It is not unusual because it is just outside the confidence interval. OC. It is not unusual because it is actually in the confidence interval. O D. It is not unusual because it is only 0.04 standard deviations above the confidence interval.

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:A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims "graded 200" on the sidewall of the tire. A random sample of n= 23 indicates a sample mean tread wear index of 189.9 and a sample standard deviation of 27.1. Complete parts (a) through (c). a. Assuming that the population of tread wear indexes is normally distributed, construct a 99% confidence interval estimate of the population mean tread wear index for tires produced by this manufacturer under this brand name, 173.97 sus 205.83 (Round to two decimal places as needed.) b. Do you think that the consumer organization should accuse the manufacturer of producing tires that do not meet the perfomance information on the sidewall of the tire? Explain. O A. Yes, because a grade of 200 is not in the interval. OB. Yes, because a grade of 200 is in the interval. C. No, because a grade of 200 is in the interval. O D. No, because a grade of 200 is not in the interval. C. Explain why an observed tread wear index of 207 for a particular tire is not unusual, even though it is outside the confidence interval developed in (a). O A. It is not unusual because it is only 0.63 standard deviations above the sample mean. O B. It is not unusual because it is just outside the confidence interval. O C. It is not unusual because it is actually in the confidence interval. O D. It is not unusual because it is only 0.04 standard deviations above the confidence interval.

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