statistic QAs

MAT 240 – Applied Statistics Spring 2016

Computer Project: Hypothesis Tests and Confidence intervals in Minitab

Express

Introduction: For this project, you will apply your understanding of

hypothesis testing to several applications. You will use Minitab Express software to perform hypothesis

tests and construct confidence intervals.

Instructions for performing one-sample hypothesis tests and confidence intervals in Minitab Express are

posted in the Projects section of Blackboard in the file: InstructionsHypothesisTestsInMinitab.Pdf.

You will prepare a report with answers to the questions for each of the three problems below. Be sure to

include any statistics and/or graphs to support your answers and claims about the problems.

An outline for how your work will be assessed (called a grading rubric) is in the Projects section on

Blackboard.

Problem 1: A manufacturing process produces ball bearings with diameters of 0.5 centimeters. The

quality control manager of a ball bearing manufacturer wants to determine if the manufacturing process is

producing ball bearings of the proper size. Ball bearings with diameters that are too small or too large are

not acceptable. The quality control manager takes a random sample of 18 ball bearings. The results are

given in the file: BallBearings.xls. Is the manufacturing process working properly?

1) Check the conditions for conducting a hypothesis test. 2) State the null and alternative hypotheses for a hypothesis test of the sample data.

3) Using Minitab Express, conduct a hypothesis test (use  = 0.01) and construct a 99% confidence interval.

4) What is the p-value for the hypothesis test? 5) What does the confidence interval mean? 6) State the conclusion.

Problem 2: Studies suggest that about 10% of the world’s population is left-handed. A random sample of

500 U.S. students from grades 4 to 12 was taken. In this sample, 39 students said they were left-handed.

Does this sample suggest that the percentage of U.S. students who are left-handed is different from 10%?

Data were obtained from Census at School (http://www.amstat.org/censusatschool/index.cfm), an

international classroom project of the American Statistical Association.

1) Check the conditions for conducting a hypothesis test. 2) State the null and alternative hypotheses for a hypothesis test of the sample data.

3) Using Minitab Express, conduct a hypothesis test (use  = 0.05) 4) What is the p-value for the hypothesis test? 5) State the conclusion.