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course Mth 271

Student Name: assignment #003

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003.

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09:54:20

Note that there are four questions in this assignment.

`q001. Sketch a graph similar to that you constructed for the stock values, this time for the depth of the water vs. clock time (depths 80, 40, 20 at clock times 10, 40, 90). Your first point, for example, will be (10, 80). Connect these points with straight lines and determine the slopes of the lines.

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RESPONSE -->

40-80= -40

40-10= 30

-40/30= -1.33

20-40= -20

90-40= 50

-20/50= -.4

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09:55:11

The three points are (10, 80), (40, 40) and (90, 20).

From the first point to the second the rise is from 80 to 40, or -40, and the run is from 10 to 40, or 30. So the slope is -40 / 30 = -1.33.

From the second point to the third the rise is from 40 to 20, or -20, and the run is from 40 to 90, or 50, so the slope is -20 / 50 = -.4. Click on 'Next Picture' to see graph.

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RESPONSE -->

I got this correct .....my graph looks like this

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09:57:26

`q002. Look at your results for the slopes, and look the results for the average rates of change. What do you notice? In what way then does the graph represent the average rate of change?

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RESPONSE -->

the rise has increased by 20 and so has the run. It is inceaseing but the graph is still decreasing.

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09:58:42

The slopes and the rates of change are numerically equal. For example between the second and third points the rise of -20 represents the -20 cm change in depth and the run of 50 represents the 50 seconds required to make this change, so the slope represents the -20 cm / (50 sec) average rate of change over the second time interval. We therefore see that slope represents average rate of change.

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RESPONSE -->

I am not sure what you are saying here I dont understand why -20/50

When you got -20 / 50 above, the -20 represented the 20 cm decrease in the depth and the 50 represented the 50 second time interval over which the depth changed. So the rate of change of depth with respect to clock time was

ave rate = change in depth / change in clock time = (-20 cm) / (50 sec) = -.4 cm/s.

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10:01:34

`q003. To what extent do you think your graph with three points and straight line segments between them accurately depicts the detailed behavior of the water over the 80-second period of observation?

How do you think the actual behavior of the system differs from that of the graph?

How do you think the graph of the actual behavior of the system would differ from that of the graph you made?

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RESPONSE -->

I am really not sure ......The graph decreases and we can tell from these three points the the graph decreases more at the beginning then it starts to kind a level out more.

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10:03:02

The straight line segments would indicate a constant rate of change of depth. It is fairly clear that as depth decreases, the rate of change of depth will decrease, so that the rate of change of depth will not be constant. The graph will therefore never be straight, but will be a curve which is decreasing at a decreasing rate.

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RESPONSE -->

OK......I understand that the graph is decreasing at a decreaing rate and that the line segments indicate a constant rate of change.

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10:05:04

`q004. From the given information, do you think you can accurately infer the detailed behavior of the water depth over the 80-second period? Do you think you can infer the detailed behavior better than you could the values of the stocks? Why or why not?

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RESPONSE -->

I think that it is a very good indicator to the graph of water change because at first it is going to come out faster then it is going to start slowing down because there isnt enough water force behind it so this is a good graph for that.......This is not a good graph for the stock market becausee the stock market is very unpredictable

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10:05:36

It will turn out that three data points will be sufficient to infer the detailed behavior, provided the data are accurate. However you might or might not be aware of that at this point, so you could draw either conclusion. However it should be clear that the behavior of the water depth is much more predictable than the behavior of the stock market. We don't know on a given day whether the market will go up or down, but we do know that if we shoot a hole in the bottom of a full bucket the water level will decrease, and we expect that identical holes in identical buckets should result in the same depth vs. clock time behavior.

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RESPONSE -->

I understand this and I think that I did an ok job explaining this

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See my notes and let me know if you have questions.