A Print Shop Has Four Jobs That Have to Be

question 4

Essay

A print shop has four jobs that have to be processed through their only five-color press.They usually use the first-come first-served method of scheduling jobs.However, the customers are waiting in the lobby for these jobs so the shop wants to minimize the average waiting time.They are going to use the shortest processing time rule to do so.Processing times for each job are as follows (assume this is the arrival order): Job A, 30 minutes; Job B, 17 minutes; Job C, 12 minutes; Job D, 39 minutes.
a.In what order should the four jobs be done using the shortest processing time rule?
b.What is the average waiting (flow) time for all jobs using the shortest processing time rule?
c.What is the averaging waiting (flow) time using their usual first-come first-served rule?

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Definitions:

Nitrification

A microbial process by which ammonia is converted into nitrate, an important step in the nitrogen cycle.

Ammonium

A positively charged ion (NH4+) formed by the addition of a hydrogen ion to ammonia (NH3).

Nitrates

Salts or esters of nitric acid, containing the NO3- ion, commonly used in fertilizers.

Nitrogenous Compounds

Organic or inorganic compounds containing nitrogen in various chemical forms, important in many biological processes and industrial applications.