Worksheet 6 1. The life span of an electronic chip used in a high-powered micro computer is estimated to be 623.35 hours from a random sample of 12 chips. The sample variance was 400 hours. The manufacturer claims that the true mean life of the electronic chips is 633 hours. a. Construct a 95% confidence interval for the true mean life of a chip. b. What assumption have you made in your answer to a)? c. Does your confidence interval indicate that the manufacturer's claim is untrue? d. Is a confidence interval the best method to test the manufacturer's claim? Why or why not?