ENCV 800503 MANAJEMEN SISTIM REKAYASA & NILAI (SYSTEMS ENGINEERING & ANALYSIS 7 VALUE ENGINEERING) 2015

Chemical Engineering Department Faculty of Engineering, University of Indonesia

Graduate Program (S-2) HW Assignment 3: Decision Making Tree Analysis (Due 18 March 2015): Homework must be submitted in hand written. Problem -1: [30%] A production system is being planned, and three configuration alternatives are being considered. The first alternative costs Rp.500m, the second alternative costs Rp.540m, and the third alternative costs Rp.600m. With proper maintenance, all the alternatives will last for 20 years. The annual operational and maintenance costs will depend on the alternative and the production level: Alternative Production Level Annual PV Costs First High/Medium/Low Rp.10m / Rp.8m / Rp.7m Second High/Medium/Low Rp.7m / Rp.6m / Rp.5m Third High/Medium/Low Rp.5m / Rp.4m / Rp.3m It is estimated that the probability of low and high production levels are 20% and 30%, respectively. Determine the probability of medium production level [15%] Prepare a complete decision tree. [35%] Decide the alternative giving the minimum expected cost. [50%] Problem 2:[35%] Pada suatu proyek bangunan auditorium, diperlukan 10,000 lempengan baja untuk konstruksi atapnya. Lempengan baja ini dapat diperoleh melalui berbagai cara, antara lain:(1) Memproduksinya pada pabrik yang dimiliki oleh perusahaan konstruksi tersebut; (2) Membelinya langsung dari stok manufaktur lain;(3) Menyerahkan proses pengadaan material ini kepada subkontraktor pekerjaan atap. Estimasi biaya tahunan dan probabilitasnya dapat dilihat pada tabel di bawah ini.

Alternatif Keputusan Outcomes / Dampak Probabilitas

Biaya tahunan untuk 10,000 unit ($)

Memproduksi sendiri

Pabrik A 0.3 250,000 Pabrik B 0.5 400,000 Pabrik C 0.2 350,000

Membeli langsung dari stok manufaktur lain

Jumlah stok < 10,000 (membayar lebih mahal)

0.2 550,000

Jumlah stok = 10,000 0.7 250,000 Jumlah stok > 10,000, (terpaksa membeli semuanya)

0.1 290,000

Subkontraktor Pengiriman yang tepat waktu

0.5 175,000

Pengiriman yang terlambat, lalu terpaksa membeli stok manufaktur lain

0.5 450,000

ENCV 800503 MANAJEMEN SISTIM REKAYASA HW-3 MARCH 2015 Page 1

ENCV 800503 MANAJEMEN SISTIM REKAYASA & NILAI (SYSTEMS ENGINEERING & ANALYSIS 7 VALUE ENGINEERING) 2015

Alternatif mana yang layak untuk dipilih? Buatlah decision tree & Expected Monetary Value-nya dan jelaskan jawabannya.

Problem 3:[35%] Arthrodax Company has been approached by Ranger Sound with a rush order offer to purchase 100 units of a customized version of Arthrodax's Sound Screamer audio mixer at $5,000 per unit, and Arthrodax needs to decide how to respond. The electronic modifications of the standard Sound Screamer needed for this customized version are straightforward, but there will be a fixed cost of $100,000 to design the modifications and set up for assembly of the customized Sound Screamers, regardless of the number of units produced. It will cost $2,000 per unit to manufacture the circuit boards for the units. Since Arthrodax has some short term spare manufacturing capacity, the Ranger offer is potentially attractive. However, the circuit boards for the customized units will not fit into the standard Sound Screamer case, and Arthrodax must decide what to do about acquiring cases for the customized units as it decides whether to accept Ranger's purchase offer. An appropriate case can be purchased at $500 per case, but Arthrodax could instead purchase an injection molder to make the cases. It will cost $20,000 to purchase the molder, and there is a 0.6 probability that it will be possible to successfully make the cases using the molder. If the molder does not work, then the purchase price for the molder will be totally lost and Arthrodax must still purchase the cases at $500 per case. If the molder works, then it will cost $60 per case to make the cases using the molder. Regardless of which case is used, the cost of assembling the Sound Screamer circuit boards into the case is $20 per unit. Unfortunately, there is no way to test the molder without purchasing it. Assume that there is no other use for the molder except to make the cases for the Ranger order. (i) Draw a decision tree for Arthrodax's decision about whether to accept the Ranger offer and how to acquire the cases for the customized Sound Screamers. (ii) Using expected net profit as the decision criterion, determine the preferred course of action for Arthrodax.

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