Question

A) If X overbar equals 78​, Upper S equals 11​, and n equals 16​, and assuming that the population is normally​ distributed, construct a 99 % confidence interval estimate of the population​ mean. Round to two decimal places as needed.

B) A consumer organization wants to estimate the actual tread wear index of a brand name of tires that claims​ "graded 150" on the sidewall of the tire. A random sample of n=16

indicates a sample mean tread wear index of 142.3 and a sample standard deviation of 24.6.

Complete parts​ (a) through​ (c).

a.	Assuming that the population of tread wear indexes is normally​ distributed, construct a 90% confidence interval estimate of the population mean tread wear index for tires produced by this manufacturer under this brand name.

​(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 performance information on the sidewall of the​ tire? Explain 1) No, because a grade of 150 is in the interval 2) Yes, because a grade of 150 is not the interval. 3) Yes, because a grade of 150 is in the interval 4) No, because a grade of 150 is not in the interval

Answer 1

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