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): I put 47 but it said that it is wrong?

Answer 1

z score for 95% confidence interval is 1.96.

E=2 and = 7

n= = = 47.0596

Since the sample size should be a number and 47 will give a more margin of error then required.

Hence, the required sample size is 48.

Z score for 99% ci is 2.576

n= = =81.288

Hence, the required sample size is 82.