course Mth 173

The form automatically sent the first time before I had pasted my work and so I had to resubmit, but this is in fact my first time.

That happens occasionally, and it's no problem here--very easy to identify when this happens and to delete.

?b??x?????????q??assignment #003

003.

06-21-2008

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23:08:42

`qNote 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 -->

S = rise/run= -40/30 = -4 / 3 for the first slope and for the second one S = -20 / 50 = -2 / 5

confidence assessment: 3

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23:08:52

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 -->

correct

self critique assessment: 3

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23:35:53

`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 -->

I notice that the results for the slopes and the average rates of change are close to the same. so in other words the graph comes fairly close to equally representing the average rate of change as well as the slopes

confidence assessment: 3

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23:37:30

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 -->

correct

self critique assessment: 3

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23:44:06

`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 -->

the water does not appear to be coming out at a constant rate and so I don't thing that the graph with the straight line segments accurately depict the waters behavior at all. I think the graph should start of steep and then graduall taper off as the end of the 80 sec period nears.

confidence assessment: 3

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23:44:28

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 -->

correct

self critique assessment: 3

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23:52:36

`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 -->

no I don't think that you can because we only know 3 intervals and the water level is changing so rapidly that we couldn't tell. Yes I think we could becuase stocks can go up or down while water draining from a cylinder the water level will only drop.

confidence assessment: 3

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23:52:48

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 -->

correct

self critique assessment: 3

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