Statistical Concepts: Data Simulation Confidence Intervals Normal Probabilities
ID: 3295035 • Letter: S
Question
Statistical Concepts:
Data Simulation
Confidence Intervals
Normal Probabilities
Short Answer Writing Assignment
All answers should be complete sentences.
We need to find the confidence interval for the SLEEP variable. To do this, we need to find the mean and then find the maximum error. Then we can use a calculator to find the interval, (x – E, x + E).
First, find the mean. Under that column, in cell E37, type =AVERAGE(E2:E36). Under that in cell E38, type =STDEV(E2:E36). Now we can find the maximum error of the confidence interval. To find the maximum error, we use the “confidence” formula. In cell E39, type =CONFIDENCE.NORM(0.05,E38,35). The 0.05 is based on the confidence level of 95%, the E38 is the standard deviation, and 35 is the number in our sample. You then need to calculate the confidence interval by using a calculator to subtract the maximum error from the mean (x-E) and add it to the mean (x+E).
A) Give and interpret the 95% confidence interval for the hours of sleep a student gets. (5 points)
B) Then, you can go down to cell E40 and type =CONFIDENCE.NORM(0.01,E38,35) to find the maximum error for a 99% confidence interval. Again, you would need to use a calculator to subtract this and add this to the mean to find the actual confidence interval.
Give and interpret the 99% confidence interval for the hours of sleep a student gets. (5 points)
C)Compare the 95% and 99% confidence intervals for the hours of sleep a student gets. Explain the difference between these intervals and why this difference occurs. (5 points)
Sleep (hours)
8
7
7
8
4
7
7
4
4
7
6
10
7
8
7
5
8
6
7
7
7
6
7
7
6
5
7
7
4
8
6
8
7
8
7
Explanation / Answer
a)
95 % confidence interval - (6.24647,7.12495)
we are 95 % confident that true mean lie between this confidence interval .
b)99 % confidence interval- (6.10845455,7.262974)
we are 99 % confident that true mean lie between this confidence interval .
c)
we see that 99 % confidence interval is more wide ,
this is because as we increase confidence interval , the error increase
hence CI increase
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