{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# PS 8 full - ECON 2843 Problem Set 8 1 Problem 9.6 in...

This preview shows pages 1–2. Sign up to view the full content.

ECON 2843 Problem Set 8 1. Problem 9.6 in Newbold on p. 323. A company which receives shipments of batteries tests a random sample of nine of them before agreeing to take a shipment. The company is concerned that the true mean lifetime for all batteries in the shipment should be at least 50 hours. From past experience, it is safe to conclude that the population distribution of lifetimes is normal, with standard deviation 3 hours. For one particular shipment, the mean lifetime for a sample of nine batteries was 48.2 hours. Test at the 10% level the null hypothesis that the population mean lifetime is a least 50 hours. 2. Problem 9.7 in Newbold on p. 323. A pharmaceutical manufacturer is concerned about the impurity concentration in pills, and it is anxious that this concentration does not exceed 3%. It is known that from a particular production run, impurity concentrations follow a normal distribution with standard deviation .4%. ; A random sample of 64 pills from a production run was checked, and the sample mean impurity concentration was found to be 3.07%. a. Test at the 5% level the null hypothesis that the population mean impurity concentration is 3% against the alternative that it is more than 3%. b. Find the p-value for this test. c. Suppose that the alternative hypothesis had been two-sided rather than one- sided (with null hypothesis H 0 : μ = 3). State, without doing the calculations, whether the p-value of the test would be higher than, lower than, or the same as that found in part (b). Sketch a graph to illustrate your reasoning. d. In the context of this problem, explain why a one-sided alternative hypothesis is more appropriate than a two-sided alternative.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern