From Engineering Economics and Problem Solving: 4N4

Structural Engineering Solved Problems
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Engineering economy solution manual sullivan 15th ed. Used by engineering students worldwide, this best-selling text provides a sound understanding of the principles, basic concepts, and methodology of engineering economy. Built upon the rich and time-tested teaching materials of earlier editions, it is extensively revised and updated to. Techniques for solving optimization problems such as these. This chapter (and appendix) focuses on the use of differential calculus to solve certain types of optimization problems. In Web Chapter B, linear-programming techniques, used in solving con-strained optimization problems, are examined. Optimization techniques are a powerful set of tools. 116 ENGINEERING ECONOMICS Factor Table - i = 0.50% n P/F P/A P/G F/P F/A A/P A/F A/G 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 30 40 50 60 100.

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These are questions from previous years' exams and midterms. They do not reflect the questions I will ask, but should be suitable for practice. Many practice problems are available in the textbooks for the economics section of the course.

Question 1: A small aerospace company is evaluating two alternatives: the purchase of an automatically fed machine or a manually fed machine. All projects in the company are expected to return at least 10% (before tax). The auto-fed machine has an initial cost of $23,000, an estimated salvage value of $4000 and a predicted life of ten years. The expected production rate is 8 tons per hour, and the operating costs are $12 per hour. The annual maintenance cost is expected to be $3500.

The manually fed machine has a purchase price of $8000, $0 salvage value, a 5-year life and a production rate 6 tons per hour. The operating costs are $24 per hour, and the annual maintenance cost is $1500. Some additional information:

Structural Engineering Solved Problems

Both machines produce product using the same feed material and energy, and they both produce products with the same value.
There is no delay between ordering the machine and placing it in operation.
We assume that the production (ton/year) will be the same every year
The project has a ten-year life.

How many tons per year must be produced in order to justify the higher purchase cost of the auto-fed machine? You may analyze this problem using a before tax approach (without considering taxes or depreciation).

Question 2: Generally, straight-line depreciation is more favourable to the company than double declining balance. Answer this question and concisely explain your answer.

Question 3: What are typical critical values for Payback Time (PT), Return on Original Investment (ROI), and Discounted Cash Flow (DCF). The critical values define the boundary between an attractive and unattractive project.

Question 4

For each of the investments given in the following, determine whether they can be depreciated completely in the year of there first use (expensed), depreciated over many years (as defined by tax laws) or not depreciated. All have been acquired for a profit-making company. State your answer with a short discussion for each part.

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A personal computer
Land for a plant
Laboratory glassware with a life of 9 months
Liquid inventory needed to start up and operate a chemical plant

Question 5

Give four quantitative methods for evaluating financial attractiveness. For each, provide the following.

A brief explanation/definition
One advantage
One disadvantage
Explain briefly how each measure is used to decide whether to invest or not. You must give a typical threshold value.

Question 6

Your company is establishing a new office in Calgary. You seem to be spending a lot of money. One of your co-workers says, “Don’t worry, we can depreciate the costs.”

Describe the key characteristics of costs that can be depreciated.
Explain how you determine the rate with which a specific cost is depreciated.

Question 7

Estimate the current Total Module cost to install a mixer-settler unit with six stages including interconnecting piping and pumps. The aqueous to oil ratio A:O is 1:1. The flow of aqueous feed to each unit is 9 L/s. All the units are to be rubber lined. The cost is to include nozzles and internals. The costs of tankage and crude removal are excluded.

Question 8: Many questions on the Safety topic in the course are available in the chapter written by Dr. Thomas Marlin, available on the course website.

Question 9: Final exam, 2003

You have been asked to evaluate the profitability for installing an oxygen analyzer on a boiler. You have collected the following information. Any other values that you need you must estimate based on your experience in the course; please state all assumptions clearly.

Analyzer capital cost including installation = $20,000:* Analyzer maintenance cost = $4000/year
Benefit due to reduced fuel cost = $8500/year

You can depreciate the analyzer over a 5-year life using the declining balance method. The analyzer has an expected serviceable life of 10 years without replacement.

The boiler will be operated for the next 8 years, after which it will be shutdown permanently.

The company is located in Ontario, Canada, and is profitable and expects to be so for all future years.

It is January 2, 2004. If your analysis concludes that the project is financially attractive, the equipment can be installed and put in service immediately (the operators are available and the equipment is in stock at the local suppliers).

Note, most (16) points will be given for a clear, correct formulation of the problem. The calculations should be deferred until the end of the exam, when you are sure that you have completed the other questions.

Question 10 (troubleshooting)

Final exam, 2002

The following trouble shooting scenario is provided for the distillation process in the figure that was used in Assignment 7, the depropanizer column.

The plant has been operating well for the last few weeks. One of your competitors has been having equipment outages; therefore, you have been able to increase your production rate and sales. Things have been going great! Then, the operator calls you to let you know that the laboratory analysis of the depropanizer (C-8) bottoms product contains too high a mole fraction of ethane. Your customer will not accept the propane product with this ethane concentration. When you arrive at the control center the operator shows you the historical data in the figure below. You better solve this problem!

You are not expected to completely solve this problem during the examination. Your answer must contain complete written documentation of your trouble shooting procedure.

Specifically, your answer must contain (but is not limited to) the following:

At least four hypotheses for the cause of the trouble.
At least four actions that would be useful in eliminating incorrect hypotheses and reducing to one hypothesis. These should be clearly stated and presented in the order you would request them in the plant.
An explanation of how you would use the feedback plant data for each action. For example, 'If ___ and ___ are at their normal values, then, I would conclude the hypothesis #2 is disproved because ______'

Question 11

These questions refer to the flowsheet from Assignment 7. Some rules of thumb to help:

One atmosphere is equivalent to about 10 meters of water (33 feet)
Trays in a distillation column are usually 1 foot apart (30cm)

The figure shows that tower C-8 must be a minim