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Jet Copies

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The purpose of this simulation was to create to determine if JET Copies needs to purchase a back up copier. To begin, information had to be gathered which was given based on research the founders of JET Copies did to determine the length of time between breakdowns, the probability of repair times, and the revenue they would take in daily. Because there is a variance amongst the days it would take to repair the copier as well as the revenue being lost, creating this simulation helps JET Copies make the best decisions considering all the possibilities through sampling and probability. While it would be more accuracy to follow the physical process to make the decision based on true, random occurrences, JET Copies wants to know the number of breakdowns and repair time for a year which calls for this simulation of random numbers. To begin this simulation the repair time table had to be computed because it would give an introduction overview of the probability of the repair time needed to fix any breakdowns; it would also be needed to fulfill some details in the next table as well. Based on this table the following information was gathered: the probability that it would take one to two days to repair a breakdown would be 65 percent whereas for it to take three days or more would be 90 percent. After this table was created it was time to focus on the main table of the simulation which would provide more detailed information from a probability basis. The first column of the second table was to list the number of breakdowns that might occur within a year, and for this table I stopped at 13 breakdowns per year and this will be explained later in this paper. Next, because this simulation is using random numbers, random numbers had to be created, also known as pseudorandom numbers, generated by the computer following the formula =RAND(). After the random numbers had been generated next the time between breakdowns had to be calculated and to do this I used the formula =6*SQRT(C12), which the number in the parentheses was substituted for the corresponding number in column B. This formula, also known as the continuous cumulative probability, was determined based on the following function: f(x)=x squared/36, with x representing the time between breakdowns. After the formula is computed it can be assumed that, based on chance, it could take anywhere for two to six weeks before another breakdown occurs. Based on the cumulative time I could also assume that there should be about 13 breakdowns per year because there are 52 weeks in a year; for the breakdown of 13 there is the cumulative time of 52.64. The next two columns in the simulation, Columns F and G, determine the estimated repair time in days for each breakdown. While the probability of the repair time has already been calculated, what is being formulated now is the probability of repair time in occurrence of chance. To begin this formulation, another set of random numbers needed to be generated from the formula =RAND(). This set needed to be different from the first set in order for this simulation to be true as well as for the numbers to be considered truly random or pseudorandom numbers. After the random numbers are generated next was time to compute the repair time based on both the random numbers and the probability from the first table. The formula to compute the repair time was =VLOOKUP(F12,Lookup,2). The word VLOOKUP, I assume even though I have no clarity, represents looking up the values for the values in the parentheses which are the random numbers, the table representing the days of repair time in addition to their cumulative probability (which was renamed Lookup), and 2. Now all that information has either been gathered or calculated it was time to calculate the revenue that could be lost due the breakdown and determine if a backup copier was needed. Because the revenue for the business had a variance between 2000 and 8000 copies being sold for ten cents per day another set of random numbers were needed to represent the chance number of copies sold. The formula used to determine the lost of revenue = (6*RAND() + 2)*100. The part of 6*RAND() represents the probability function while 2 is the two thousand copies estimated to be sold on a daily basis and then is multiplied by one hundred to represent the a thousand times ten cents. This formula was good to compute for repair times that were just one day but for two day more the formula (6*RAND()+2) must be added in addition to the original formula for each additional day. The determined loss of revenue based on probability after 13 breakdowns for a year would be $11966.58 . Based on the information provided by the simulation a backup copier is not needed because the loss of revenue is less than the determining $12000.00 factor agreed upon by JET Copies. Based on the simulation I feel confident in my answer that they should not purchase a backup copier, however based on how closely the revenue lost calculation is to the twelve thousand dollar limit I would suggest the consideration of purchasing a backup copier. The reason I would suggest considering the purchase of a backup copier is because this is a simulation based on chance, or random number, it does not mean that there is only going to be thirteen breakdowns the whole year or that the maximum lose is going to $11966.58. In addition, the loss of revenue seemed to mostly be based on the random chance of the repair time being two days or less and that is not always going to be the case for each breakdown. This simulation is a great example of a real world situation because there are many limits and variances. One limit could be expressed by the repair time in days for any breakdown. While this was introduced as a probability gathered from research information, it could also be a limitation because depending on the type of breakdown it could be longer than four days and based on how busy the repair business is, business hours of the repair business, and so on; it is a dependent variable based on another independent variable. Another limit to the study was the variance of the revenue gained on a daily basis, which was two thousand to eight thousand copies being sold at ten cents a copy, and determining what the loss would be for each day the copier was broken down. In addition, the limit of twelve thousand as being the determining factor of whether another copier must be purchased or not could be seen as a limit of the study.

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