assignment 12

course mth 272

If your solution to a stated problem does not match the given solution, you should self-critique per instructions at

http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm.

Your solution, attempt at solution: If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.

012. `query 12

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

Question: `q5.6.26 (was 5.6.24 trap rule n=4, `sqrt(x-1) / x on [1,5]

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

(5-1)/4 = 1

So you get the following (1, 2), (2, 3), (3, 4), (4,5)

Plug this in to the equation (`sqrt(x-1) / x) and you get the following

f(1) = 0

f(2) = .5

f(3) = .471

f(4) = .433

f(5) = .4

(0+.25)/2 + (.5+471)/2 + (.471 + .433)/2 + (.433+.4)/2 = 1.605

confidence rating #$&*3

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

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

Given Solution:

`a Dividing [1, 5] into four intervals each will have length ( 5 - 1 ) / 4 = 1. The four intervals are therefore

[1, 2], [2, 3], [3, 4], [4,5].

The function values at the endpoints f(1) = 0, f(2) = .5, f(3) = .471, f(4) = .433 and f(5) = .4. The average altitudes of the trapezoids are therefore

(0 + .5) / 2 = 0.25, (.5 + .471)/2 = 0.486, (.471 + .433) / 2 = 0.452 and (.433 + .4) / 2 = 0.417.

Trapeoid areas are equal to ave height * width; since the width of each is 1 the areas will match the average heights 0.25, 0.486, 0.452, 0.417.

The sum of these areas is the trapezoidal approximation 1.604. **

DER

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

Self-critique (if necessary):

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

Self-critique rating #$&*3

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

Question: `q5.6.32 (was 5.6.24 est pond area by trap and midpt (20 ft intervals, widths 50, 54, 82, 82, 73, 75, 80 ft).

How can you tell from the shape of the point whether the trapezoidal or midpoint estimate will be greater?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

(0 + 50) / 2 = 25

(50 + 54) / 2 = 52

(54 + 82) / 2 = 68

(82 + 82) / 2 = 82

(0 + 50) / 2 = 25

(82 + 73) / 2 = 77.5

(73 + 75) / 2 = 74

(75 + 80) / 2 = 77.5

(80 + 0) / 2 = 40

20 (25+52+68+82+77.5+74+77.5+40)= 9920 ft^2

confidence rating #$&* 2

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

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

Given Solution:

`a Since widths at 20-ft intervals are 50, 54, 82, 82, 73, 75, 80 ft the pond area can be approximated by a series of trapezoids with these altitudes. The average altitudes are therefore respectively

(0 + 50 / 2) = 25

(50 + 54) / 2 = 52

(54 + 82) / 2 = 68

(82 + 82) / 2 = 82

etc., with corresponding areas

25 * 20 = 500

52 * 20 = 1040

etc., all areas in ft^2.

The total area, according to the trapezoidal approximation, will therefore be

20 ft (25+52+68+82+77.5+74+77.5+40) ft = 9920 square feet.

The midpoint widths would be calculated based on widths at positions 10, 30, 50, 70, ..., 150 ft. Due to the convex shape of the pond these estimates and will lie between the estimates made at 0, 20, 40, ..., 160 feet.

The convex shape of the pond also ensures that the midpoint of each rectangle will 'hump above' the trapezoidal approximation, so the midpoint estimate will exceed the trapezoidal estimate. **

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

Self-critique (if necessary):

I could not figure out how to do the midpoint on this shape. After reading this I understand.

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

Self-critique rating #$&*3

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

Question: `q Add comments on any surprises or insights you experienced as a result of this assignment.

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

Self-critique (if necessary):

None at the moment

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

Self-critique rating #$&*

"

&#Very good responses. Let me know if you have questions. &#