4. Suppose a bank branch, located in a residential area, is concerned with its service during the noon-to-1 pm lunch hour. The waiting times, in minutes, collected from a sample of 15 customers during this hour, are listed below. Complete parts (a) through (d) below.

9.585.897.945.898.783.878.038.39

10.436.755.644.036.149.875.49

a.a. Compute the mean and median.

The mean is _________(Round to two decimal places as needed.)

The median is ________(Do not round.)

b. Compute the variance, standard deviation, range, coefficient of variation, and Z scores. Are there any outliers? Explain.

The variance is _______(Round to three decimal places as needed.)

The standard deviation is _________(Round to three decimal places as needed.)

The range is (Do not round.)

The coefficient of variation is _____%.(Round to two decimal places as needed.)

Compute the Z scores.

(Round to two decimal places as needed.)

Data (X)Z Score

9.58_____

5.89_____

7.94_____

5.89______

8.78______

3.87_____

8.03______

8.39______

10.43______

6.75______

5.64_______

4.03_______

6.14_______

9.87_______

5.49______

Are there any outliers? Explain.

A. Yes, since there is at least one Z score that is less than minus3.0 or greater than plus3.0.

B. Yes, since there are no Z scores that are less than minus3.0 or greater than plus3.0.

C. No, since there are no Z scores that are less than minus3.0 or greater than plus3.0.

D. No, since there is at least one Z score that is less than minus3.0 or greater than plus3.0.

c. Are the data skewed? If so, how? Choose the correct response below.

A. Yes comma the data are left dash skewed because the mean is less than the median.

B. No comma the data are not skewed because the mean and median are equal.

C. Yes comma the data are right dash skewed because the mean is greater than the median.

d. As a customer walks into the branch office during the lunch hour, he asks the branch manager how long he can expect to wait. The branch manager replies, "Almost certainly less than 5 minutes." On the basis of the results of (a) through (c), evaluate the accuracy of this statement.

Choose the correct response below.

A. Since the range of values is greater than 5 minutes, the customer is likely to experience a waiting time in excess of 5 minutes.

B. Since the mean and median are both greater than 5 minutes, the customer is likely to experience a waiting time in excess of 5 minutes.

C. Although both the mean and median are greater than 5 minutes, all values greater than 5 minutes have a Z score greater than plus3.0, thus they are outliers. This means the branch manager's statement is accurate.