1/ Let x be a random variable that is described by a normal probability distribution. What percent of all possible obser

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1/ Let x be a random variable that is described by a normal
probability distribution. What percent of all possible observed
values of x are within two standard deviations of the mean?
2/ What value is at the center of a confidence interval for the
population mean?
x¯
μ
σ/√n
z^α/2
2/For a fixed level of confidence, what happens to a confidence
interval for μμ when we increase the sample size?
  The width of the interval will decrease.
   The width of the interval will increase.
   We need more information to answer this
question.
   The width of the interval will not change.