# Statistics

Chapter review questions attached.

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1. If it is important to reject a false null hypothesis, the B probability should be:

a. small

b. large

c. close to 1.0

d. negative

e. impossible to tell?

3.. The manufacturer of a refrigerator system for beer kegs produces refrigerators which are supposed to maintain a true mean temperature, of 47 degrees F, ideal for a certain type of German pilsner. The owner of the brewery does not agree with the refrigerator manufacturer, and will conduct a hypothesis test to determine whether the true mean temperature differs from this value.

Classify the hypothesis test as two-tailed, right tailed, or left tailed.

a. two-tailed

b. right-tailed

c. left-tailed

4. At one school, the average amount of time that tenth-graders spend watching television each week is 21.6 hours. The principal introduces a campaign to encourage the students to watch less television. One year later, the principal wants to perform a hypothesis test to determine whether the average amount of time spent watching television per week has decreased from the previous mean of 21.6 hours.

Classify the hypothesis test as two-tailed, right tailed, or left tailed.

5. Jenny is conducting a hypothesis test concerning a population mean. The hypotheses are as follows.

H0: = 50

Ha: > 50

She selects a sample and finds that the sample mean is 54.2. She then does some calculations and is able to make the following statement:

If H0were true, the chance that the sample mean would have come out as big ( or bigger) than 54.2 is 0.3. Do you think that she should reject the null hypothesis? Why or why not?

a. No, she should not reject the null hypothesis, the observed sample mean is consistent with the null hypothesis.

b. No, she should not reject the null hypothesis, the observed sample mean is not consistent with the null hypothesis.

c. Yes, she should reject the null hypothesis, the observed sample mean is consistent with the null hypothesis.

d.Yes, she should reject the null hypothesis, the observed sample mean is not consistent with the null hypothesis.

6.

Traditionally in hypothesis testing the null hypothesis represents the "status quo" which will be overturned only if there is evidence against it. Which of the statements below might represent a null hypothesis?

a. the treatment has no effect

b. the defendant is guilty

c. the teaching method raises SAT scores

d. A new brand of battery lasts longer than Brand A batteries

8. A manufacturer claims that the mean amount of juice in its 16 ounce bottles is 16.1 ounces. A consumer advocacy group wants to perform a hypothesis test to determine whether the mean amount is actually less than this. The hypotheses are:

H0: = 16.1 ounces

Ha: < 16.1 ounces

Suppose that the results of the sampling lead to rejection of the null hypothesis. Classify that conclusion as a Type I error, a Type II error, or a correct decision, if in fact the mean amount of juice is less than 16.1 ounces.

9. In 1990, the average duration of long-distance telephone calls originating in one town was 9.4 minutes. A long-distance telephone company wants to perform a hypothesis test to determine whether the average duration of long-distance phone calls has changed from the 1990 mean of 9.4 minutes. The hypotheses are:

H0: = 9.4 minutes

Ha: > 9.4 minutes

a.Type I error

b. Type II error

c. Correct Decision

13.

The significance level of a hypothesis test is 0.33. What is the probability of a Type I error? Express your answer as a decimal.

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(See attached file for full problem description)

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