Question

In a test of the effectiveness of garlic for lowering cholesterol, 50 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes (beforeminusafter) in their levels of LDL cholesterol (in mg/dL) have a mean of 4.2 and a standard deviation of 15.5. Construct a 90% confidence interval estimate of the mean net change in LDL cholesterol after the garlic treatment. What does the confidence interval suggest about the effectiveness of garlic in reducing LDL cholesterol? Click here to view a t distribution table.LOADING... Click here to view page 1 of the standard normal distribution table.LOADING... Click here to view page 2 of the standard normal distribution table.LOADING... What is the confidence interval estimate of the population mean mu? nothing mg/dLless thanmuless than nothing mg/dL (Round to two decimal places as needed.) What does the confidence interval suggest about the effectiveness of the treatment

Answer #1

As we are not given here that the distribution is normal, but the sample size is greater than 30, therefore we can use the Central limit theorem here to get the distribution of sample mean as a normal distribution.

For n - 1 = 49 degrees of freedom, we get from t distribution
tables here:

P( t49 < 1.677 ) = 0.95

Therefore, due to symmetry, we have here:

P( -1.677 < t49 < 1.677) = 0.9

Therefore the confidence interval here is obtained as:

**This is the required 90% confidence interval for the
population mean here.**

As the whole confidence interval lies above 0, therefore we have sufficient evidence here that there is a significant mean net change in LDL cholesterol after the garlic treatment at the 90% confidence that is 10% level of significance.

In a test of the effectiveness of garlic for lowering
cholesterol, 50 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (beforeminusafter) in their levels of LDL
cholesterol (in mg/dL) have a mean of 3.2 and a standard deviation
of 18.5. Construct a 95% confidence interval estimate of the mean
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In a test of the effectiveness of garlic for lowering
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tablet form. Cholesterol levels were measured before and after the
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In a test of the effectiveness of garlic for lowering
cholesterol, 45 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (beforeminusafter) in their levels of LDL
cholesterol (in mg/dL) have a mean of 2.9 and a standard deviation
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In a test of the effectiveness of garlic for lowering
cholesterol,
4848
subjects were treated with garlic in a processed tablet form.
Cholesterol levels were measured before and after the treatment.
The changes
(beforeminus−after)
in their levels of LDL cholesterol (in mg/dL) have a mean
of
4.14.1
and a standard deviation of
17.817.8.
Construct a
9595%
confidence interval estimate of the mean net change in LDL
cholesterol after the garlic treatment. What does the confidence
interval suggest about the effectiveness...

In a test of the effectiveness of garlic for lowering
cholesterol, 49 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (beforeminusafter) in their levels of LDL
cholesterol (in mg/dL) have a mean of 3.7 and a standard deviation
of 19.3. Construct a 95% confidence interval estimate of the mean
net change in LDL cholesterol after the garlic treatment. What does
the confidence interval suggest about the effectiveness...

In a test of the effectiveness of garlic for lowering
cholesterol, 49 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (before minus after) in their levels of
LDL cholesterol (in mg/dL) have a mean of 3.9 and a standard
deviation of 19.1. Construct a 99% confidence interval estimate of
the mean net change in LDL cholesterol after the garlic treatment.
What does the confidence interval suggest about...

In a test of the effectiveness of garlic for lowering
cholesterol, 42 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (before−after) in their levels of LDL
cholesterol (in mg/dL) have a mean of 4.9 and a standard deviation
of 16.9. Construct a 95% confidence interval estimate of the mean
net change in LDL cholesterol after the garlic treatment. What does
the confidence interval suggest about the effectiveness...

In a test of the effectiveness of garlic for lowering
cholesterol, 50 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (beforeminus− after) in their levels of LDL
cholesterol (in mg/dL) have a mean of 4.1and a standard deviation
of 16.3 Construct a 99 % confidence interval estimate of the mean
net change in LDL cholesterol after the garlic treatment. What does
the confidence interval suggest about the...

In a test of the effectiveness of garlic for lowering
cholesterol, 42 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (before−after) in their levels of LDL
cholesterol (in mg/dL) have a mean of 4.9 and a standard deviation
of 15.4. Construct a 99% confidence interval estimate of the mean
net change in LDL cholesterol after the garlic treatment. What does
the confidence interval suggest about the effectiveness...

In a test of the effectiveness of garlic for lowering
cholesterol, 50 subjects were treated with garlic in a processed
tablet form. Cholesterol levels were measured before and after the
treatment. The changes (beforeminusafter) in their levels of LDL
cholesterol (in mg/dL) have a mean of 4.8 and a standard deviation
of 19.6. Construct a 99% confidence interval estimate of the mean
net change in LDL cholesterol after the garlic treatment. What does
the confidence interval suggest about the effectiveness...

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