Exam 9: Statistical Inference: Hypothesis Testing for Single Populations

The weight of a USB flash drive is 30 grams and is normally distributed.Periodically,quality control inspectors at Dallas Flash Drives randomly select a sample of 17 USB flash drives.If the mean weight of the USB flash drives is too heavy or too light the machinery is shut down for adjustment; otherwise,the production process continues.The last sample showed a mean and standard deviation of 31.9 and 1.8 grams,respectively.Using $\alpha$ = 0.10,the critical "t" values are _______.

The executives of CareFree Insurance,Inc.feel that "a majority of our employees perceive a participatory management style at CareFree." A random sample of 200 CareFree employees is selected to test this hypothesis at the 0.05 level of significance.Eighty employees rate the management as participatory.The appropriate decision is __________.

A company believes that it controls more than 30% of the total market share for one of its products.To prove this belief,a random sample of 144 purchases of this product is contacted.It is found that 50 of the 144 purchased this company's brand of the product.If a researcher wants to conduct a statistical test for this problem,the alternative hypothesis would be _______.

The probability of type II error becomes bigger if the level of significance is changed from 0.01 to 0.05.

Suppose you are testing the null hypothesis that a population mean is less than or equal to 46,against the alternative hypothesis that the population mean is greater than 46.The sample size is 25 and alpha =.05.If the sample mean is 50 and the population standard deviation is 8,the observed z value is _______.