Brian vanecek, vp of operations at portland trust bank, is evaluating the service level provided to walk-in customers. accordingly, his staff recorded the waiting times for 64 randomly selected walk-in customers and determined that their mean waiting time was 15 minutes. assume that the population standard deviation is 4 minutes. the 95% confidence interval for the population mean of waiting times is . 14.02 to 15.98b. 7.16 to 22.84c. 14.06 to 15.94d. 8.42 to 21.58e. 19.80 to 23.65

A. 14.02 to 15.98

Step-by-step explanation:

Let denotes the mean waiting time for population.

Given : Sample size : n= 64

Sample mean :   (minutes)

Population standard deviation =

Confidence level : 95%

By z-table , the critical values for 95% confidence = z*=1.96

Confidence interval for population mean :

The 95% confidence interval for the population mean of waiting times will be :

Hence, the 5% confidence interval for the population mean of waiting times is 14.02 to 15.98.

Thus , the correct answer is Option A.