Assignment 25

#$&*

course MTH 272

12/14 about 3:05 pm

???I do not see an assignment 25???

********************************************* Question: `qQuery problem 7.3.38 level curves of z = e^(xy), c = 1, 2, 3, 4, 1/2, 1/3, 1/4. YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: Solve the function e^(xy)=c for y Ln(e^(xy)) = ln(c) Xy=ln(c) Y=ln(c) / x Plugging the above values c in you get the following: C Y x=1 x=-1 Points 1 0 2 .7/x .7 -.7 (1,.7)(-1,-.7) 3 1.1/x 1.1 -1.1 (1,1.1)(-1,-1.1) 4 1.4/x 1.4 -1.4 (1,1.4)(1,-1.4) (1/2) -.7/x -.7 .7 (1,-.7)(-1,.7) (1/3) -1.1/x -1.1 1.1 (1,-1.1)(-1,1.1) (1/4) -1.4/x -1.4 1.4 (1,-1.4)(-1,1.4) All functions are asymptotic to the x and y axis, except for c=1 which is the y axis. The fractional values for c create the inverse of the graph which flips the quadrants for which the curve lies in. confidence rating #$&*:3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution: `a The z = c level curve of e^(xy) occurs when e^(xy) = c. We solve e^(xy) = c for y in terms of x. We first take the natural log of both sides: ln(e^(xy)) = ln(c), or xy = ln(c). We then divide both sides by x: y = ln(c) / x. For c = 1 we get y = ln(1) / x = 0 / x = 0. Thus the c = 1 level curve is the x axis y = 0. For c = 2 we get y = ln(2) / x = .7 / x, approximately. This curve passes through the points (1,.7) and (-1, -.7), and is asymptotic to both the x and y axes. For c = 3 we get y = ln(3) / x = 1.1 / x, approximately. This curve passes through the points (1,1.1) and (-1, -1.1), and is asymptotic to both the x and y axes. For c = 4 we get y = ln(4) / x = 1.39 / x, approximately. This curve passes through the points (1,1.39) and (-1, -1.39), and is asymptotic to both the x and y axes. For c = 1/2 we get y = ln(1/2) / x = -.7 / x, approximately. This curve passes through the points (-1,.7) and -1, -.7), and is asymptotic to both the x and y axes. For c = 1/3 we get y = ln(1/3) / x = -1.1 / x, approximately. This curve passes through the points (-1,1.1) and -1, -1.1), and is asymptotic to both the x and y axes. For c = 1/4 we get y = ln(1/4) / x = -1.39 / x, approximately. This curve passes through the points (-1,1.39) and -1, -1.39), and is asymptotic to both the x and y axes. The c = 2, 3, 4 level curves form similar hyperbolas in the first and third quadrant which progressively 'bunch up' closer and closer together. Similar behavior is observed for the c = 1/2, 1/3, 1/4 hyperbolas, which occur in the second and fourth quadrants. STUDENT COMMENT I had a little bit of trouble applying my graphing here given dimension, but clear pertaining to concept, making a bit more progress. INSTRUCTOR RESPONSE You should be very familiar with the graph of y = 1 / x. Focus on the point (1, 1) and the fact that the graph in the right half-plane has asymptotes with the positive y and positive x axes. If you multiply this function by ln(c) the point becomes (1, ln(c)). For c = 1, 2, 3, 4 the points rise higher and higher, but with less space between successive points. The level curves pass through these points, still with asymptotes at the x and y axes. Each curve is a bit 'higher' than the preceding. &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary):OK ------------------------------------------------ Self-critique Rating:OK ********************************************* Question: `qQuery problem 7.3.46 queuing model W(x,y) = 1 / (x-y), y < x (y = ave arrival rate, x = aver service rate). What are the values of W at (15, 10), (12, 9), (12, 6) and (4,2)? YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: w(15,10)=1/5 w(12,9)=1/3 w(12,6)=1/6 w(4,2)=1/2 confidence rating #$&*:3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution: `a 1/5, 1/3, 1/6, 1/2 &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary):OK ------------------------------------------------ Self-critique Rating:OK ********************************************* Question: `qYou may take extra time with the following: What is the nature of the worst combination of x and y, and why is this bad--both in terms of the behavior of the function and in terms of the real-world situation? YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: Since w(x,y) represents the time the customer waits in hours, you want the result as close to zero as possible, which would be a larger number in the denominator, y to be larger than x. The worse scenario would be the result closest to one where y is slightly larger than x, meaning w(x,y) would be almost 1. confidence rating #$&*:3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution: `aGood answer by student: x=service, y=arrival rate therefore the worst senerio would be when the arrival rate was almost as long as the service rate...its worse to have a customer waiting a long time than having a customer being served for a long time &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary):OK ------------------------------------------------ Self-critique Rating:OK ********************************************* Question: `qQuery Add comments on any surprises or insights you experienced as a result of this assignment. "

Self-critique (if necessary): ------------------------------------------------ Self-critique rating: ________________________________________ `gr91 #$&*

Assignment 25

#$&*

course MTH 272

12/14 about 3:05 pm

???I do not see an assignment 25???

*********************************************

Question: `qQuery problem 7.3.38 level curves of z = e^(xy), c = 1, 2, 3, 4, 1/2, 1/3, 1/4.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Solve the function e^(xy)=c for y

Ln(e^(xy)) = ln(c)

Xy=ln(c)

Y=ln(c) / x

Plugging the above values c in you get the following:

C Y x=1 x=-1 Points

1 0

2 .7/x .7 -.7 (1,.7)(-1,-.7)

3 1.1/x 1.1 -1.1 (1,1.1)(-1,-1.1)

4 1.4/x 1.4 -1.4 (1,1.4)(1,-1.4)

(1/2) -.7/x -.7 .7 (1,-.7)(-1,.7)

(1/3) -1.1/x -1.1 1.1 (1,-1.1)(-1,1.1)

(1/4) -1.4/x -1.4 1.4 (1,-1.4)(-1,1.4)

All functions are asymptotic to the x and y axis, except for c=1 which is the y axis.

The fractional values for c create the inverse of the graph which flips the quadrants for which the curve lies in.

confidence rating #$&*:3

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`a The z = c level curve of e^(xy) occurs when e^(xy) = c.

We solve e^(xy) = c for y in terms of x. We first take the natural log of both sides:

ln(e^(xy)) = ln(c), or

xy = ln(c). We then divide both sides by x:

y = ln(c) / x.

For c = 1 we get y = ln(1) / x = 0 / x = 0. Thus the c = 1 level curve is the x axis y = 0.

For c = 2 we get y = ln(2) / x = .7 / x, approximately. This curve passes through the points (1,.7) and (-1, -.7), and is asymptotic to both the x and y axes.

For c = 3 we get y = ln(3) / x = 1.1 / x, approximately. This curve passes through the points (1,1.1) and (-1, -1.1), and is asymptotic to both the x and y axes.

For c = 4 we get y = ln(4) / x = 1.39 / x, approximately. This curve passes through the points (1,1.39) and (-1, -1.39), and is asymptotic to both the x and y axes.

For c = 1/2 we get y = ln(1/2) / x = -.7 / x, approximately. This curve passes through the points (-1,.7) and -1, -.7), and is asymptotic to both the x and y axes.

For c = 1/3 we get y = ln(1/3) / x = -1.1 / x, approximately. This curve passes through the points (-1,1.1) and -1, -1.1), and is asymptotic to both the x and y axes.

For c = 1/4 we get y = ln(1/4) / x = -1.39 / x, approximately. This curve passes through the points (-1,1.39) and -1, -1.39), and is asymptotic to both the x and y axes.

The c = 2, 3, 4 level curves form similar hyperbolas in the first and third quadrant which progressively 'bunch up' closer and closer together. Similar behavior is observed for the c = 1/2, 1/3, 1/4 hyperbolas, which occur in the second and fourth quadrants.

STUDENT COMMENT

I had a little bit of trouble applying my graphing here given dimension, but clear pertaining to concept, making a bit more progress.

INSTRUCTOR RESPONSE

You should be very familiar with the graph of y = 1 / x. Focus on the point (1, 1) and the fact that the graph in the right half-plane has asymptotes with the positive y and positive x axes.

If you multiply this function by ln(c) the point becomes (1, ln(c)). For c = 1, 2, 3, 4 the points rise higher and higher, but with less space between successive points. The level curves pass through these points, still with asymptotes at the x and y axes. Each curve is a bit 'higher' than the preceding.

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):OK

------------------------------------------------

Self-critique Rating:OK

*********************************************

Question: `qQuery problem 7.3.46 queuing model W(x,y) = 1 / (x-y), y < x (y = ave arrival rate, x = aver service rate).

What are the values of W at (15, 10), (12, 9), (12, 6) and (4,2)?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

w(15,10)=1/5

w(12,9)=1/3

w(12,6)=1/6

w(4,2)=1/2

confidence rating #$&*:3

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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Given Solution:

`a 1/5, 1/3, 1/6, 1/2

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Self-critique (if necessary):OK

------------------------------------------------

Self-critique Rating:OK

*********************************************

Question: `qYou may take extra time with the following: What is the nature of the worst combination of x and y, and why is this bad--both in terms of the behavior of the function and in terms of the real-world situation?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

Since w(x,y) represents the time the customer waits in hours, you want the result as close to zero as possible, which would be a larger number in the denominator, y to be larger than x. The worse scenario would be the result closest to one where y is slightly larger than x, meaning w(x,y) would be almost 1.

confidence rating #$&*:3

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.............................................

Given Solution:

`aGood answer by student:

x=service, y=arrival rate

therefore the worst senerio would be when the arrival rate was almost as long as the service rate...its worse to have a customer waiting a long time than having a customer being served for a long time

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Self-critique (if necessary):OK

------------------------------------------------

Self-critique Rating:OK

*********************************************

Question: `qQuery Add comments on any surprises or insights you experienced as a

&#Your work looks good. Let me know if you have any questions. &#