Chapter 5.1 Examples
5.10 Total sleep time of college students.
, the total sleep time per
night among college students was approximately Normally distributed with mean
hours and standard deviation
= 1.15 hours. Suppose you plan to take an SRS of size
200 and compute the average total sleep time.
What is the standard deviation for the average time?
Use the 95 part of the 68–95–99.7 rule to describe the variability of this sample mean.
What is the probability that your average will be below 6.9 hours?
5.11 Determining sample size.
Recall the previous exercise. Suppose you want to use a
sample size such that about 95% of the averages fall within ±5 minutes of the true mean