Suppose that we choose a sample of twenty (20) USF students and we find that and
ID: 3236342 • Letter: S
Question
Suppose that we choose a sample of twenty (20) USF students and we find that and s = 2.8. Sample mean is 139
1.Find the 94% confidence interval for the population mean.
2.Does this interval seem reasonable know that the mean of the population is actually = 135?Why?
3.What would happen to the confidence interval if we increased the sample size?
4.What would happen to the confidence interval if we increased the confidence level?
Section II
1.Given the previous information where same mean = 135 and our sample is and s = 2.8 (again with n = 20), is there a significant difference in our sample compared to the population?(Yes, I know there is no given significance level.)
Explanation / Answer
Answer:
Suppose that we choose a sample of twenty (20) USF students and we find that and s = 2.8. Sample mean is 139
1.Find the 94% confidence interval for the population mean.
Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation
2.8
Sample Mean
139
Sample Size
20
Confidence Level
94%
Intermediate Calculations
Standard Error of the Mean
0.626099034
Degrees of Freedom
19
t Value
2.0000
Interval Half Width
1.2522
Confidence Interval
Interval Lower Limit
137.75
Interval Upper Limit
140.25
94% CI for mean = (137.75, 140.25).
2.Does this interval seem reasonable know that the mean of the population is actually = 135?Why?
No, because 135 not contained in the 94% confidence interval.
3.What would happen to the confidence interval if we increased the sample size?
if we increase the sample size, width of the confidence interval will decrease.
4.What would happen to the confidence interval if we increased the confidence level?
if we increase confidence level, width of the confidence interval will increase.
Section II
1.Given the previous information where same mean = 135 and our sample is and s = 2.8 (again with n = 20), is there a significant difference in our sample compared to the population?(Yes, I know there is no given significance level.)
At 94% level, there is a significant difference in our sample compared to the population because 135 not falls inside the 94% confidence interval.
Confidence Interval Estimate for the Mean
Data
Sample Standard Deviation
2.8
Sample Mean
139
Sample Size
20
Confidence Level
94%
Intermediate Calculations
Standard Error of the Mean
0.626099034
Degrees of Freedom
19
t Value
2.0000
Interval Half Width
1.2522
Confidence Interval
Interval Lower Limit
137.75
Interval Upper Limit
140.25
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