Garden Sky is an apartment complex at Waverley Glen in Victoria. Garden Sky management promotes apartments at the complex stating that if any issue arises, their maintenance person will be dispatched within one hour. If a tenant waits for the maintenance person more than one hour, Garden Sky management will give $10 for each additional block of 15 minutes waiting up to a maximum of $20. A delay under 15 minutes is also paid $10. For example, if the additional delay is 25 minutes, the management gives $10 for the first 15 minutes delay and another $10 for the other 10 minutes delay. Requests for the maintenance person’s attention is done over the phone and are recorded. A study has found that the number of calls requiring maintenance has the following distribution.

Time between calls for repairman (minutes)	Probability
30	0.15
60	0.30
90	0.30
120	0.25

Some jobs require more time than others because of variation in the difficulty of repairs. Parts needed for most repairs are available in the storage room at the complex. However, for certain types of jobs, parts have to be purchased from Bunnies Warehouse at Notting Hill. If the required parts are available at the store room, the maintenance person completes the job before attending to the next job (call). All jobs that come when the repairman is attending to a job or away from apartment complex site picking up new part/s will wait until the repairman is free. A trip (drive, pick up and return) to Bunnies Warehouse takes approximately 1 hour. Generally, 10 per cent of the jobs require part/s not on site.

If all required parts are available on site, time to fix the problem is distributed as follows.

Time for repair (minutes)	Probability
30	0.45
60	0.30
90	0.20
120	0.05

A job that requires parts from Bunnies Warehouse takes approximately 1 hour to complete. The cost of salary for the maintenance person is $120 per hour. Maintenance persons works 12-hour shifts. Maintenance service is offered 24 hours of the day. (i)Use simulation to estimate total cost of delays in a 24-hour day. Repeat the simulation 30 times.
(ii)Draw a histogram of cost of delays using 8 bins of equal width (0-$100, $100-$200,…..,$700-$800).
(iii)State any assumption/s you are making.

(iv)What advice would you give Garden Sky management to improve their repair service operation.