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(5a). At a bank, the tellers on average take 11 minutes per customer, with a sta

ID: 426417 • Letter: #

Question

(5a). At a bank, the tellers on average take 11 minutes per customer, with a standard deviation of 9 minutes. What is the coefficient of variation of the service time? (Provide the answer as a decimal number, not a percentage; provide two significant digits to the right of the decimal point) (b). A project has seven activities - A, B, C, D, E, F, and G. They have mean activity times of 12, 15, 18, 9, 14, 10, and 8 days respectively, and each of them have a standard deviation of 2 days. The critical path has been identified as B-E-F- G. What is the standard deviation of the project completion time?

Explanation / Answer

(5a) Coefficient of variation of service time

= Standard deviation / Mean service time

= 9/11

= 0.82

(b)

Variance of the project completion time

= Sum of variances of critical activities (Variance is the square of standard deviation)

= 22+22+22+22 = 16

Standard deviation of the project completion time

= Square root of variance

= SQRT(16)

= 4