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=25 indicates a sample mean tread wear index of 189.2 and a sample standard deviation of 20.7. Complete parts (a) through (c). Click here to view page 1 of the critical values for the Distribution. Click here to view page 2 of the critical values for the Distribution a. Assuming that the population of tread wear indexes is normally distributed, construct a 95% confidence interval estimate of the population mean tread wear index for tiros 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 perfomance information on the sidewall of the tire? Explain