Suppose that a phone company reports that the average duration of a cell phone call is 1.4 minutes, with a standard deviation of 1.2 minutes.
1. Would it be reasonable to use a normal distribution to model the duration of cell phone calls? Explain, based primarily on the values reported above.
2. Suppose you want to examine a random sample of 60 cell phone calls. Do you think it would be reasonable to use the Central Limit Theorem to describe the sampling distribution of the sample mean call duration? Explain.
3. What does the CLT say about the sampling distribution of the sample mean call duration in a random sample of 60 calls?
4. Draw a well-labeled sketch to accompany your answer to question 3.
5. Describe how the sketch would change if the sample size were 160 calls rather than 60 calls.