00:01
Okay, so for question 1, we need to describe a state space to model this system.
00:09
So let x of t denote the state of machine 1, and y of t denote the state of machine 2.
00:20
So x of t is defined as whether it is functioning, broken, but not being repaired, or being repaired.
00:29
And y of t is defined in a similar way.
00:34
But given the priority of repairs, the state space can be simplified.
00:40
So we need to consider whether machine 1 is being repaired and machine 2 is waiting, machine 2 is being repaired or neither machine is being repaired.
00:56
Since the repairman stops repairing machine 2 whenever machine 1 breaks down, we do not need to track the interrupted repairs for machine 2 separately.
01:07
So, we define the system as this.
01:12
State 0, both machines are operational.
01:21
State 1, machine 1 is broken and being repaired.
01:28
Machine 2 might be operational or broken but not being repaired.
01:42
State 2, machine 1 is operational.
01:44
Machine 2 is broken and being repaired.
02:28
Now, to determine the transition rates between these states, the rate of transition from state 0 to state 1 is 3 per hour.
02:37
This is the broken down rate of machine 1...