Exam 9: Introduction to Hypothesis Testing

A report recently published in a major business periodical stated that the average salary for female managers is less than $50,000.If we were interested in testing this,the following null and alternative hypotheses would be established: .

In hypothesis testing,the null hypothesis should contain the equality sign.

A company that makes shampoo wants to test whether the average amount of shampoo per bottle is 16 ounces.The standard deviation is known to be 0.20 ounces.Assuming that the hypothesis test is to be performed using 0.10 level of significance and a random sample of n = 64 bottles,how large could the sample mean be before they would reject the null hypothesis?

The cost of a college education has increased at a much faster rate than costs in general over the past twenty years.In order to compensate for this,many students work part- or full-time in addition to attending classes.At one university,it is believed that the average hours students work per week exceeds 20.To test this at a significance level of 0.05,a random sample of n = 20 students was selected and the following values were observed: Based on these sample data,which of the following statements is true?

A large tire manufacturing company has claimed that its top line tire will average more than 80,000 miles.If a consumer group wished to test this claim,the research hypothesis would be: : μ > 80,000 miles.

In a two-tailed hypothesis test the area in each tail of the rejection region is equal to α.

A company that makes and markets a device that is aimed at helping people quit smoking claims that at least 70 percent of the people who have used the product have quit smoking.To test this,a random sample of n = 100 product users was selected.Of these,65 people were found to have quit smoking.Given these results,the test statistic value is z = -1.0911.

The police chief in a local city claims that the average speed for cars and trucks on a stretch of road near a school is at least 45 mph.If this claim is to be tested,the null and alternative hypotheses are: H_o : μ < 45 mph H_a : μ ≥ 45 mph

If we are performing a two-tailed test of whether μ = 100,the probability of detecting a shift of the mean to 105 will be ________ the probability of detecting a shift of the mean to 110.

When someone has been accused of a crime the null hypothesis is: H_o : innocent. In this case Type I error would be convicting an innocent person.

The Gordon Beverage Company bottles soft drinks using an automatic filling machine.When the process is running properly,the mean fill is 12 ounces per can.The machine has a known standard deviation of 0.20 ounces.Each day,the company selects a random sample of 36 cans and measures the volume in each can.They then test to determine whether the filling process is working properly.The test is conducted using a 0.05 significance level.What is the critical value in ounces?

A cell phone company believes that 90 percent of its customers are satisfied with their service.They survey n = 30 customers.Based on this,it is acceptable to assume the sample distribution is normally distributed.

Which of the following would be an appropriate null hypothesis?

The following is an appropriate statement of the null and alternate hypotheses for a test of a population mean:

A company that makes and markets a device that is aimed at helping people quit smoking claims that at least 70 percent of the people who have used the product have quit smoking.To test this,a random sample of n = 100 product users was selected.The critical value for the hypothesis test using a significance level of 0.05 would be approximately -1.645.

If the probability of a Type I error is set at 0.05,then the probability of a Type II error will be 0.95.

A contract with a parts supplier calls for no more than .04 defects in the large shipment of parts.To test whether the shipment meets the contract,the receiving company has selected a random sample of n = 100 parts and found 6 defects.If the hypothesis test is to be conducted using a significance level equal to 0.05,what is the test statistic and what conclusion should the company reach based on the sample data?

A one-tailed hypothesis for a population mean with a significance level equal to .05 will have a critical value equal to z = .45.

A major airline has stated in an industry report that its mean onground time between domestic flights is less than 18 minutes.To test this,the company plans to sample 36 randomly selected flights and use a significance level of .10.Assuming that the population standard deviation is known to be 4.0 minutes,if the true population mean is 16 minutes,the decision maker could end up making either a Type I or a Type II error depending on the sample result.

Whenever possible,in establishing the null and alternative hypotheses,the research hypothesis should be made the alternative hypothesis.