In developing patient appointment schedules, a medical center wants to estimate the mean time that a staff member spends with each patient. How large a sample should be taken if the desired margin of error is two minutes at a 95% level of confidence? How large a sample should be taken for a 99% level of confidence? Use a planning value for the population standard deviation of 7 minutes.

Question

a. 95% Confidence (to the nearest whole number):

b. 99% Confidence (to the nearest whole number):

Answer 1

Formula:

n = {[(z-value)(sd)]/E}^2

a) n = [(1.96 * 7)/2]^2

b) n = [(2.575 * 7)/2)^2

Calculate. Round to the next highest whole number.