Question

Question 10 options:

A department has 5 machines that each run for an average of 8.4 hours (exponential) before service is required. Service time average is 1.6 hours (exponential).

N = 5

T = 1.6

U = 8.4

X = T / ( T + U) = 1.6 / (1.6 + 8.4) = 1.6 / 10 = .16

From Table:

M	D	F
1	0.695	0.869
2	0.13	0.988

With 2 servers, what is the probability that a machine would be served immediately when it requires service?

P( Served Immediately) = 1 - D =

(Format .xx)

Suppose machine downtime cost is $100 per hour per machine, and server time costs $30 per hour.

Downtime Cost (N - J) * $100
J = NF(1-X)

For M = 1
J = 3.65
Downtime Cost = $

Format xxx.xx No $ Sign
Server Cost = $30
Total Cost = $

Format xxx.xx No $ Sign

For M = 2
J = 4.15
Downtime Cost = $85
Server Cost = $

Format xx No $ Sign
Total Cost = $

Format xxx.xx No $ Sign

For M = 3
J =

Format x.xx
Downtime Cost = $

Format xxx.xx No $ Sign
Server Cost = $

Format xx No $ Sign
Total Cost = $

Format xxx.xx No $ Sign


To Keep Cost at a Minimum, the optimal number of servers =

Answer 1