The EPA claims that fluoride in children’s drinking water should be at a mean level of less than 1.2 ppm, or parts per million, to reduce the number of dental cavities. Identify the Type I error. (Points : 1)
[removed] Fail to support the claim σ < 1.2 when σ < 1.2 is true.
[removed] Support the claim μ < 1.2 when μ = 1.2 is true.
[removed] Support the claim σ < 1.2 when σ = 1.2 is true.
[removed] Fail to support the claim μ < 1.2 when μ < 1.2 is true.
2.
Medical researchers studying two therapies for treating patients infected with Hepatitis C found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions np ≥ 5 and nq ≥ 5 are satisfied.
Therapy 1
Therapy 2
Number of patients
39
47
Eliminated Hepatitis
20
13
C infection
Construct a 95% confidence interval estimate of the odds ratio of the odds for having Hepatitis C after Therapy 1 to the odds for having Hepatitis C after Therapy 2. Give your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)
[removed]
3.Researchers studying sleep loss followed the length of sleep, in hours, of 10 individuals with insomnia before and after cognitive behavioral therapy (CBT). Assume a .05 significance level to test the claim that there is a difference between the length of sleep of individuals before and after CBT. Also, assume the data consist of matched pairs, the samples are simple random samples, and the pairs of values are from a population having a distribution that is approximately normal.
Individual
1
2
3
4
5
6
7
8
9
10
Before
6
5
4
5
3
4
5
3
4
2
CBT
After
8
8
7
6
7
6
6
5
7
5
CBT
Construct a 95% confidence interval estimate of the mean difference between the lengths of sleep. Give your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)
[removed]
4.
The paired data consist of the cost of regionally advertising (in thousands of dollars) a certain pharmaceutical drug and the number of new prescriptions written (in thousands).
Cost
9
2
3
4
2
5
9
10
Number
85
52
55
68
67
86
83
73
Find the predicted value of the number of new prescriptions written if $6000 is spent in regional advertising. Give your answer as an integer. (Points : 0.5)
[removed]
5.
Use a .05 significance level and the observed frequencies of 144 drownings at the beaches of a randomly selected coastal state to test the claim that the number of drownings for each month is equally likely.
