Part A) John wonders if the extrusion machine at ACME Auto Parts is working properly. From experience, he knows the widths of the parts are normally distributed. He takes a simple random sample of fourteen parts, and the sample standard deviation of the widths is 1.02 mm. Help him make a 95% confidence interval for the true standard deviation. Be sure to interpret the interval in a complete sentence. Part B) John also wonders about the variation in assembly times for some of the parts at ACME Auto Parts. In the past, these times have been distributed normally with mean 185 minutes and standard deviation 8 minutes (or variance of 64 minutes2). However, he thinks that due to some recent new hires that this variance has increased. He decides to run a hypothesis test to check this. In a sample of size 49, the sample variance was 77 minutes2. Write the null and alternative hypotheses, calculate the test statistic, and obtain the p-value. Address the necessary assumptions and state your conclusions in a complete sentence. Please explain how to find both part A and part B of Question 1! Thank you!
Part A) John wonders if the extrusion machine at ACME Auto Parts is working properly. From experience, he knows the widths of the parts are normally distributed. He takes a simple random sample of fourteen parts, and the sample standard deviation of the widths is 1.02 mm. Help him make a 95% confidence interval for the true standard deviation. Be sure to interpret the interval in a complete sentence.
Part B) John also wonders about the variation in assembly times for some of the parts at ACME Auto Parts. In the past, these times have been
Please explain how to find both part A and part B of Question 1! Thank you!
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