$5-12.$ The lead time is the period between the placement of an order and its receipt. Using historical records, a manufacturing firm has developed the following probability distribution for its lead time $($in weeks$)$ from a key supplier:

A$)$ Calculate the expected $($average$)$ lead time for the component.

B$)$ Calculate the variance and standard deviation for the delivery lead time.

C$)$ Compute the coefficient of variation for the delivery lead time.

D$)$ How might the manufacturer use this information in its decision making?