Question

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 10 minutes.

95% Confidence (to the nearest whole number):  

99% Confidence (to the nearest whole number):  

Answer 1

Solution :

a) Z/2 = Z0.025 = 1.96  

sample size = n = [Z/2* / E] 2

n = [ 1.96 * 10 / 2]2

n = 96.04

Sample size = n = 97

b) Z/2 = Z0.005 = 2.576

sample size = n = [Z/2* / E] 2

n = [ 2.576 * 10 / 2]2

n = 165.89

Sample size = n = 166