Question

Time spent using email per session is normally distributed with µ of 8 minutes, with a...

Time spent using email per session is normally distributed with µ of 8 minutes, with a population standard deviation (σ) of 2 minutes. A sample of 25 sessions is drawn.

For this problem, be sure to use the z-calculation that is for sample means, and includes the sample size:

It is important that you understand why you use this expression here.

  1. What is the probability that a sample mean will be between 7.8 and 8.2 minutes?
  2. What is the probability that a sample mean will be between 7.5 and 8.0 minutes?
  3. Why do I need to state that the distribution of measures of time spent using email per session is normal in order to do parts a and b of this problem? Please answer in a single sentence.
  4. Is the normal distribution a “continuous” or a “discrete” distribution? In a single sentence, explain why?

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