Question 315840: A consumer advocacy group is doing a large study on car rental practices. Among other things, the consumer group would like to do a statistical test regarding the mean monthly mileage, , of cars rented in the U.S. this year. The consumer group has reason to believe that the mean monthly mileage of cars rented in the U.S. this year is less than last year's mean, which was miles.
The group plans to do a statistical test regarding the value of . It chooses a random sample of monthly mileages and computes the mean of the sample to be miles and the standard deviation to be miles.
1 What is the null hypothesis and the alternate hypothesis that should be used for the test?
2. In the context of this test, what is the Type II error? ( A type two error _______ the hypothesis that U is _________ ________ when in fact u is _______ ________)
3. Suppose the group decides not to reject the hypothesis. What sort of error might it be making ____?
Now I beleive I got the first part:
HO: u is less than 2850
H1: u is not equal to 2850
I just having a hard time understanding the other part
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A consumer advocacy group is doing a large study on car rental practices. Among other things, the consumer group would like to do a statistical test regarding the mean monthly mileage, of cars rented in the U.S. this year. The consumer group has reason to believe that the mean monthly mileage of cars rented in the U.S. this year is less than last year's mean, which was 2850 miles.
The group plans to do a statistical test regarding the value of . It chooses a random sample of monthly mileages and computes the mean of the sample to be miles and the standard deviation to be miles.
1 What is the null hypothesis and the alternate hypothesis that should be used for the test?
Ho: u >= 2850 miles
Ha: u < 2850 miles
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Comment: Equality must ALWAYS be included in Ho.
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2. In the context of this test, what is the Type II error?
(A type two error is failing to reject the null hypothesis that u is greater than or equal to 2850 when in fact u is not greater than or equal to 2850)
3. Suppose the group decides not to reject the hypothesis. What sort of error might it be making. A type II error.
Note: A type I error is the probability you reject Ho when in fact Ho is true
A type II error is the probabioliity you fail to reject Ho when in fact Ho
is false.
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Cheers,
Stan H.
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