Unit Test — Unit test Answers

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A real-estate agent conducted an experiment to test the effect of selling a staged home vs. selling an empty home. To do so, the agent obtained a list of 10 comparable homes just listed for sale that were currently empty. He randomly assigned 5 of the homes to be "staged,” meaning they were filled with nice furniture and decorated. The owners of the 5 homes all agreed to have their homes staged by professional decorators. The other 5 homes remained empty. The hypothesis is that empty homes are not as appealing to buyers as staged homes and, therefore, sell for lower prices than staged homes. The mean selling price of the 5 empty homes was $150,000 with a standard deviation of $22,000. The mean selling price of the 5 staged homes was $175,000 with a standard deviation of 35,000. A dotplot of each sample shows no strong skewness and no outliers.

A
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 < 0
B
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 > 0
C
H0: x̄1 – x̄2 = 0, Ha: x̄1 – x̄2 < 0
D
H0: x̄1 – x̄2 = 0, Ha: x̄1 – x̄2 > 0
22
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Can a person train to become better at holding their breath? An experiment was designed to find out. Twelve volunteers were randomly assigned to 1 of 2 groups. The 6 volunteers assigned to group 1 were given breath-holding exercises to perform for 2 weeks. The other group was not given any information about the experiment. At the end of the 2 weeks, all 12 volunteers were individually tested to determine how long they could hold their breath. Here are the data (in seconds).Group 1: 90, 88, 70, 110, 75, 105Group 2: 40, 48, 35, 50, 55, 62

A
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 < 0
B
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 > 0
C
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 ≠ 0
D
H0: μ1 – μ2 = 0, Ha: μ1 – μ2 = 0
23

From previous experience, the owner of an apple orchard knows that the mean weight of Gala apples is 140 grams. There has been more precipitation than usual this year. The owner believes the weights of the apples will be heavier than usual and therefore the crop will be more profitable. This will allow the owner to expand the orchard. The owner takes a random sample of 30 apples and records their mean weight. What is the consequence of a Type I error in this situation?

A
The owner believes the crop will be more profitable and expands the orchard when the true mean weight of the apples is actually greater than 140 grams.
B
The owner believes the crop will not be more profitable and does not expand the orchard when the true mean weight of the apples is actually greater than 140 grams.
C
The owner believes the crop will be more profitable and expands the orchard when the true mean weight of the apples is actually not greater than 140 grams.
D
The owner believes the crop will not be more profitable and does not expand the orchard when the true mean weight of the apples is actually not greater than 140 grams.
24

From previous experience, the owner of an apple orchard knows that the mean weight of Gala apples is 140 grams. There has been more precipitation than usual this year. The owner believes the weights of the apples will be heavier than usual and therefore the crop will be more profitable. The owner takes a random sample of 30 apples and records their mean weight. What is a Type II error in this situation?

A
Based on the sample mean, the owner concludes that the mean weight of apples is greater than 140 grams when the true mean weight is not greater than 140 grams.
B
Based on the sample mean, the owner concludes that the mean weight of apples is not greater than 140 grams when the true mean weight is not greater than 140 grams.
C
Based on the sample mean, the owner concludes that the mean weight of apples is greater than 140 grams when the true mean weight is greater than 140 grams.
D
Based on the sample mean, the owner concludes that the mean weight of apples is not greater than 140 grams when the true mean weight is greater than 140 grams.
25

A headache medication is supposed to contain 500 mg of active ingredient. A researcher would like to test the hypotheses =500 versus 500 where μ = the true amount of active ingredient for all pills. A 99% confidence interval based on a random sample of 60 pills is (505, 511). Based on the interval, what decision should be made at α = 0.01?

Question illustration
A
The researcher should reject the null hypothesis because 500 falls inside the 99% confidence interval.
B
The researcher should reject the null hypothesis because 500 falls outside the 99% confidence interval.
C
The researcher should fail to reject the null hypothesis because 500 falls inside the 99% confidence interval.
D
The researcher should fail to reject the null hypothesis because 500 falls outside the 99% confidence interval.

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