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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