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 7 minutes.

95% Confidence (to the nearest whole number):

99% Confidence (to the nearest whole number):

Answer 1

for 95% Confidence :

	for95% CI crtiical Z          =	1.960
	standard deviation σ=	7
	margin of error E =	2
required sample size n=(zσ/E)2                  =		47   (please try 48 if this comes wrong)

for 99% Confidence :

	for99% CI crtiical Z          =	2.576
	standard deviation σ=	7
	margin of error E =	2
required sample size n=(zσ/E)2                  =		81 (please try 82 if this comes wrong)