MATH 399N WEEK 6 iLab / MATH399N WEEK 6 iLab (New 2022/2023): STATISTICS FOR DECISION MAKING: CHAMBERLAIN COLLEGE OF NURSING

MATH 399N Statistics for Decision Making
Week 6 iLab

Name:

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).

1. Give and interpret the 95% confidence interval for the hours of sleep a student gets. (5
points)

One sample Z confidence interval:
μ : Mean of variable
Standard deviation not specified.

95% confidence interval results:
Variable n Sample Mean Std. Err. L. Limit U. Limit
Sleep 35 6.6857143 0.22741303 6.2399929 7.1314356

(6.24, 7.13)

Interpretation: It can be said with 95% certainty that the average hours the students sleep is
between 6.24 hours and 7.13 hours.

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.




MATH399 Week 6 Lab Template/ page 1