Exam 9: Fundamentals of Hypothesis Testing: One-Sample Tests

SCENARIO 9-9 The president of a university claimed that the entering class this year appeared to be larger than the entering class from previous years but their mean SAT score is lower than previous years.He took a sample of 20 of this year's entering students and found that their mean SAT score is 1,501 with a standard deviation of 53.The university's record indicates that the mean SAT score for entering students from previous years is 1,520.He wants to find out if his claim is supported by the evidence at a 5% level of significance. -Referring to Scenario 9-9,which of the following best describes the Type II error?

SCENARIO 9-10 A manufacturer produces light bulbs that have a mean life of at least 500 hours when the production process is working properly.Based on past experience,the population standard deviation is 50 hours and the light bulb life is normally distributed.The operations manager stops the production process if there is evidence that the population mean light bulb life is below 500 hours. -Referring to Scenario 9-10,if you select a sample of 100 light bulbs and are willing to have a level of significance of 0.05,the probability of the operations manager incorrectly stopping the process when the process is in fact working properly is .

An entrepreneur is considering the purchase of a coin-operated laundry.The current owner claims that over the past 5 years,the mean daily revenue was $675 with a population standard deviation of $75.A sample of 30 days reveals a daily mean revenue of $625.If you were to test the null hypothesis that the daily mean revenue was $675,which test would you use?

For a given sample size,the probability of committing a Type II error will increase when the probability of committing a Type I error is reduced.

Suppose,in testing a hypothesis about a mean,the Z test statistic is computed to be 2.04.The null hypothesis should be rejected if the chosen level of significance is 0.01 and a two-tail test is used.