A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims "graded 200" on the sidewall ofthe tire. A random sample of n = 20 indicates a sample mean tread wear index of 188.2 and a sample standard deviation of 15.9. Complete parts (a) through (b). E) a. Assuming that the population of tread wear indexes is normally distributed, construct a 99% condence interval estimate of the population mean tread wear index for tires produced by this manufacturer under this brand name. S p 5 (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 ofthe tire? Explain. . Yes, because a grade of 200 is in the interval. No, because a grade of 200 is in the interval. . Yes, because a grade of 200 is not in the interval. No, because a grade of 200 is not in the interval. A paper manufacturer has a production process that operates continuously throughout an entire production shift. The paper is expected to have a mean length of 12 inches, and the standard deviation of the length is 0.03 inch. At periodic intervals, a sample is selected to determine whether the mean paper length is still equal to 12 inches or whether something has gone wrong in the production process to change the length of the paper produced. A random sample of 100 sheets is selected, and the mean paper length is 11.999 inches. A 90% confidence interval estimate for the population mean paper length is 1 1.99407 5 us 12.00394. Is it true that you do not know for sure whether the population mean is between 11.99407 ant 12.00394 inches? Explain. Choose the correct answer below. It is true because the population mean will be in the interval only 10% of the time. It is false because the sample mean falls outside the interval. It is true because the population mean will be in the interval only 90% of the time. 9.0!\"? It is false because the sample mean falls within the interval