As an Aid to the Establishment of Personnel Requirements,the Director $\bar { X }$

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, $\bar { X }$ = 19.8 and s² = 25.Which of the following assumptions is necessary in order for a confidence interval to be valid?

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