As an Aid to the Establishment of Personnel Requirements, the Director

Multiple Choice

As an aid to the establishment of personnel requirements, the director of a hospital wishes to estimate the mean number of people who are admitted to the emergency room during a 24-hour period. The director randomly selects 64 different 24-hour periods and determines the number of admissions for each. For this sample, $\overline{X }= 19.8$ and s² = 25. Which of the following assumptions is necessary in order for a confidence interval to be valid?

A) The population sampled from has an approximate t distribution.
B) The mean of the sample equals the mean of the population.
C) The population sampled from has an approximate normal distribution.
D) None of these assumptions are necessary.