Exam 9: Hypothesis Tests

A researcher is testing a new painkiller that claims to relieve pain in less than 15 minutes, on average. a.State the hypotheses associated with the researcher's test. b.Describe a Type I error for this situation. c.Describe a Type II error for this situation.

In the hypothesis testing procedure,  is

A carpet company advertises that it will deliver your carpet within 15 days of purchase. A sample of 49 past customers is taken. The average delivery time in the sample was 16.2 days. Assume the population standard deviation is known to be 5.6 days. a.State the null and alternative hypotheses. b.Using a critical value, test the null hypothesis at the 5% level of significance. c.Using a p-value, test the hypothesis at the 5% level of significance. d.What type of error may have been committed for this hypothesis test?

Nancy believes that the average running time of movies is equal to 140 minutes. A sample of 4 movies was taken and the following running times were obtained. Assume the distribution of the population is normally distributed. a.State the null and alternative hypotheses. b.Using a critical value, test the hypothesis at the 10% level of significance. c.Using a p-value, test the hypothesis at the 10% level of significance. d.Using a confidence interval, test the hypothesis at the 10% level of significance. e.Could a Type II error have been committed in this hypothesis test?

When the p-value is used for hypothesis testing, the null hypothesis is rejected if

At a certain manufacturing plant, a machine produces ball bearings that should have a diameter of 0.500 mm. If the machine produces ball bearings that are either too small or too large, the ball bearings must be scrapped. Every hour, a quality control manager takes a random sample of 36 ball bearings to test to see if the process is "out of control" (i.e. to test to see if the average diameter differs from 0.500 mm). Assume that the process is maintaining the desired standard deviation of .06 mm. The results from the latest sample follow: At a .01 level of significance, use Excel to test whether the process is "out of control."

When the hypotheses H₀:   100 and H_a:   100 are being tested at a level of significance of , the null hypothesis will be rejected if the test statistic z is

For each shipment of parts a manufacturer wants to accept only those shipments with at most 10% defective parts. A large shipment has just arrived. A quality control manager randomly selects 50 of the parts from the shipment and finds that 6 parts are defective. Is this sufficient evidence to reject the entire shipment? Use a .05 level of significance to conduct the appropriate hypothesis test.

A sample of 16 cookies is taken to test the claim that each cookie contains at least 9 chocolate chips. The average number of chocolate chips per cookie in the sample was 7.875 with a standard deviation of 1. Assume the distribution of the population is normal. a.State the null and alternative hypotheses. b.Using a critical value, test the hypothesis at the 1% level of significance. c.Using a p-value, test the hypothesis at the 1% level of significance. d.Compute the probability of a Type II error if the true number of chocolate chips per cookie is 8.

Exhibit 9-3 -Refer to Exhibit 9-3. The test statistic equals

When the rejection region is in the lower tail of the sampling distribution, the p-value is the area under the curve

The practice of concluding "do not reject H₀" is preferred over "accept H₀" when we

The sponsors of televisions shows targeted at the market of 5 - 8 year olds want to test the hypothesis that children watch television at most 20 hours per week. The population of viewing hours per week is known to be normally distributed with a standard deviation of 6 hours. A market research firm conducted a random sample of 30 children in this age group. The resulting data follows: At a .10 level of significance, use Excel to test the sponsors' hypothesis.

In hypothesis testing, the hypothesis tentatively assumed to be true is

If a hypothesis is rejected at a 5% level of significance, it

A two-tailed test is performed at a 5% level of significance. The p-value is determined to be 0.09. The null hypothesis

As a general guideline, the research hypothesis should be stated as the

Which of the following is an improper form of the null and alternative hypotheses?

In order to determine the average price of hotel rooms in Atlanta, a sample of 64 hotels was selected. It was determined that the average price of the rooms in the sample was $112. The population standard deviation is known to be $16. Use a 0.05 level of significance and determine whether or not the average room price is significantly different from $108.50.

For a two-tailed hypothesis test about a population mean, the null hypothesis can be rejected if the confidence interval