population mean of the wait times in the drive thru for all customers To do so you select a random sample of 40 of the chain s drive thru customers and record the wait time in the drive thru for each Assume it is known that the population standard deviation of the wait times in the drive thru for the taco chain s restaurants is 2 79 minutes Based on your sample follow the steps below to construct a 95 confidence interval for the population mean of the wait times in the drive thru for all customers If necessary consult a list of formulas a Click on Take Sample to see the results from your random sample of 40 customers b Take Sample Sample size 0 Point estimate 0 Population standard deviation 0 Critical value 0 Enter the values of the sample size the point estimate for the population mean the population standard deviation and the critical value you need for your 95 confidence interval Choose the correct critical value from the table of critical values provided When you are done select Compute Compute 0 00 0 00 Number of customers 2 00 Sample mean Standard error Margin of error 4 00 95 confidence interval Sample standard 95 confidence interval deviation Based on your sample enter the lower and upper limits to graph the 95 confidence interval for the population mean of the wait times in the drive thru for all customers 6 00 Confidence level 99 95 90 Population standard deviation 2 79 8 00 Critical value 0 005 2 576 0 025 1 960 20 050 1 645 10 00 10 00