midterm-key 2005

# midterm-key 2005 - CHE 4253 Midterm Exam Instructor...

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CHE 4253 - Midterm Exam Instructor: Dimitrios V. Papavassiliou November 1, 2005. Name:………………………. OU ID or SSN:……………………… Answer all questions and show your calculations, if any are necessary. 1. (18 points) Indicate whether the following statements are True or False. (a) If we use the rate of return based on discounted cash flow as the interest rate in the Net Present Worth formula, we will find that NPW < 0. TRUE FALSE The definition of the ROR based on discounted CF gives: NPW=0. (b) An investment A is more risky than another investment B, when the standard deviation of the probability density function of the profit for investment A is much lower than that of B. TRUE FALSE The higher the standard deviation, the riskier the investment . (c) An investment A is more risky than another investment B, when the expected profit for investment A is much lower than that of B. TRUE FALSE The expected profit does not reflect the risk associated with a project. The standard deviation does. (d) We can double the flow rate through a system and maintain the same pressure head by using a second similar pump connected in parallel. TRUE FALSE (e) In order to increase NPSHR, we can use a smaller impeller in our pump. TRUE FALSE As the impeller becomes larger, NPSHR becomes smaller. (f) In order to increase NPSHA, we can use a larger impeller in our pump. TRUE FALSE NPSHA refers to NPSH available by the system. The type of pump is irrelevant. 2. (10 points) Find the values of x, y and z that minimize the following objective function f(x,y,z) = 2x + 2y 2 +z 2 subject to the constraints that x + y + z = 2 and x > 0, y > 0, z > 0 Set (x + y + z -2) = 0. Introduce a Lagrange multiplier λ

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midterm-key 2005 - CHE 4253 Midterm Exam Instructor...

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