The ABCCo. factory has been having a maintenance problem with the control panel

for one of its production processes. This control panel contains four identical

electromechanical relays that have been the cause of the trouble. The problem is

that the relays fail fairly frequently, thereby forcing the control panel $($and the

production process it controls$)$ to be shut down while a replacement is made. The

current practice is to replace the relays only when they fail. The average total cost of

doing this has been Rs$.320$ per hour.

To attempt to reduce this cost, a proposal has been made to replace all four relays

whenever any one of them fails to reduce the frequency with which the control panel

must be shut down. Would this actually reduce the cost?

The pertinent data are the following. For each relay, the operating time until failure

has approximately a uniform distribution from $1,000$ to $2,000$ hours. The control panel

must be shut down for one hour to replace one relay or for two hours to replace all

four relays.

The total cost associated with shutting down the control panel and replacing relays

is Rs$\mathrm{.}1,00,000$ per hour plus Rs$\mathrm{.}20,000$ for each new relay. Develop a simulation

model to evaluate the cost of the proposal and compare it to the current practice.

Perform $10$ trials $($where the end of each trial coincides with the end of a shutdown

of the control panel$)$ and determine the average cost per hour.

$)$