Stat 1222 Homework 8: Hypothesis Testing in Statistics - Prof. Animikh Biswas, Assignments of Statistics

Download Stat 1222 Homework 8: Hypothesis Testing in Statistics - Prof. Animikh Biswas and more Assignments Statistics in PDF only on Docsity! Homework 8 Stat 1222 (Professor: Dr. Biswas) Due: Tue 4/7/09 Name: ID#: 1. A maker of microwave ovens advertises that no more than 10% of its microwaves need repair during the first five years of use. In a random sample of 57 microwaves five years old, 13% needed repairs. Test the manufacturer’s claim. (a) State the null and the alternative hypotheses. H0 : Ha : (b) Find the value of the standardized test statistic based on the observed sample. (c) Find the critical values at level α = .06 and show the rejection rule. What is your decision at α = .06. 2. A company manufactures light bulbs. The company claims that the bulbs have a mean lifetime of 1000 hours. A random sample of 21 light bulbs is randomly selected and tested. The mean lifespan of the sample is 1015 hours and the standard deviation is 25 hours. Assume that the distribution of lifetime of light bulbs is normally distributed. (a) State the null and the alternative hypotheses. H0 : Ha : (b) In the context of the problem, explain Type I error. (c) Find the value of the standardized test statistic based on the observed sample. (d) Find the critical values at level α = .05 and show the rejection rule. State your decision.