Question

12: A random sample of 50 drive-thru customers at Burger World (a subsidy of Malco, Inc.) was taken to determine the average transaction time after the order was placed during the evening rush (4:00 PM to 6:00 PM).   The edited Data Analysis output is shown below. Answer the following five questions. (3.5 pts.)

Transaction Time
Mean	3.811
Median	3.83
Mode	4.58
Standard Deviation	1.530
Sample Variance	2.340
Kurtosis	0.813
Skewness	-0.175
Range	8.23
Minimum	-0.36
Maximum	7.87
Sum	190.56
Count	50
Confidence Level(95.0%)	0.435

1. Identify the degrees of freedom and the critical value of t used in the calculation of the 95% confidence interval.

2. Calculate the lower confidence limit (LCL) and the upper confidence limit (UCL). (Round the LCL and UCL to two decimal places, (i.e., 12.13, 45.67.)

3. Interpret the confidence interval: I am _____ confident that the _________ of transaction time is between the lower confidence limit (LCL) and the upper confidence limit (UCL).

4. If the confidence level is changed to 99 percent, does the width of the confidence interval increase or decrease?

5. Would it be reasonable or plausible to conclude that the population mean is four minutes? Explain your reasoning.

6. What is the standard error of the mean? Show the SE to three decimal places, (i.e., .123).

7. What sample size is needed to reduce the standard error by half?

Answer 1