college math
posted by dannie0913 .
3.15 A bank branch located in a commercial district of a city has developed an improved process for A bank branch located in a commercial district of a city has developed an improved process for serving customers during the noonto1:00 p.m. lunch period. The waiting time, in minutes (defined as the time the customer enters the line to when he or she reaches the teller window), of a sample of 15 customers during this hour is recorded over a period of one week. The results are contained in the data file Bank1 and are listed below:
Waiting Time
4.21
5.55
3.02
5.13
4.77
2.34
3.54
3.2
4.5
6.1
0.38
5.12
6.46
6.19
3.79
a. Compute the mean and median.
b. Compute the variance, standard deviation, range, coefficient of variation, and Z scores. Are there any outliers? Explain.
c. Are the data skewed? If so, how?
"d. As a customer walks into the branch office during the lunch hour, she asks the branch manager how long she can expect to wait. The branch manager replies, “Almost
certainly less than five minutes.” On the basis of the results of (a) through (c), evaluate the accuracy of this statement."

Assuming the values are all in seconds, all the values are less than 5 minutes (300 seconds).
Median = point at which half the scores are below and half above.
The mean = sum of scores/number of scores
Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.
Standard deviation = square root of variance
Range = highest score  lowest
Z = (scoremean)/SD
I'll let you do the calculations. 
I goofed. Now I see that the values are probably minutes and decimal portions of minutes. This invalidates my first statement…ONLY.