Exam 9: Hypothesis Tests

A meteorologist stated that the average temperature during July in Chattanooga was 80 degrees. A sample of July temperatures over a 32-year period was taken. The correct set of hypotheses is _____.

In the hypothesis testing procedure, α is _____.

For a one-tailed test (upper tail) with a sample size of 900, the null hypothesis will be rejected at the .05 level of significance if the test statistic is _____.

A two-tailed test is a hypothesis test in which the rejection region is _____.

A Type I error is committed when _____.

The academic planner of a university thinks that at least 35% of the entire student body attends summer school. The correct set of hypotheses to test his belief is _____.

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 0.06 mm. The results from the latest sample follow: 0.468 0.521 0.421 0.476 0.448 0.346 0.452 0.513 0.465 0.395 0.558 0.526 0.354 0.474 0.447 0.405 0.411 0.453 0.456 0.477 0.529 0.440 0.570 0.319 0.471 0.480 0.499 0.446 0.405 0.557 0.468 0.521 0.421 0.476 0.448 0.346 At a .01 level of significance, use Excel to test whether the process is out of control.

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.

The school's newspaper reported that the proportion of students majoring in business is at least 30%. You plan on taking a sample to test the newspaper's claim. The correct set of hypotheses is _____.

The board of directors of a corporation has agreed to allow the human resources manager to move to the next step in planning day care service for employees' children if the manager can prove that at least 25% of the employees have interest in using the service. The HR manager polls 300 employees and 90 say they would seriously consider utilizing the service. At the ? = .10 level of significance, is there enough interest in the service to move to the next planning step?

A sample of 81 account balances of a credit company showed an average balance of $1,200. The population standard deviation is $126. You want to determine if the mean of all account balances is significantly different from $1,150. Use a .05 level of significance.

A soft drink filling machine, when in perfect adjustment, fills the bottles with 12 ounces of soft drink. Any overfilling or underfilling results in the shutdown and readjustment of the machine. To determine whether or not the machine is properly adjusted, the correct set of hypotheses is _____.

The sponsors of televisions shows targeted at the market of 5- to 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 follow: 19.5 29.7 17.5 10.4 19.4 18.4 14.6 10.1 12.5 18.2 19.1 30.9 22.2 19.8 11.8 19.0 27.7 25.3 27.4 26.5 16.1 21.7 20.6 32.9 27.0 15.6 17.1 19.2 20.1 17.7 At a .10 level of significance, use Excel to test the sponsors' hypothesis.

In hypothesis testing, the alternative hypothesis is _____.

Excel's __________ function can be used to calculate a p-value for a hypothesis test.

Which of the following does NOT need to be known in order to compute the p-value?

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

When using Excel to calculate a p-value for a lower-tail hypothesis test, which of the following must be used?

In the past, 75% of the tourists who visited Chattanooga went to see Rock City. The management of Rock City recently undertook an extensive promotional campaign. They are interested in determining whether the promotional campaign actually INCREASED the proportion of tourists visiting Rock City. The correct set of hypotheses is _____.

The manager of an automobile dealership is considering a new bonus plan in order to increase sales. Currently, the mean sales rate per salesperson is five automobiles per month. The correct set of hypotheses for testing the effect of the bonus plan is _____.