To determine the effect of temperature on the yield of a certain chemical process, the process is run 24 times at various temperatures. The temperature (in ? C) and the yield (expressed as a percentage of a theoretical maximum) for each run are given in the following table. The results are presented in the order in which they were run, from earliest to latest.
|
Order
|
Temp
|
Yield
|
Order
|
Temp
|
Yield
|
Order
|
Temp
|
Yield
|
|
1
|
30
|
49.2
|
9
|
25
|
59.3
|
17
|
34
|
65.9
|
|
2
|
32
|
55.3
|
10
|
38
|
64.5
|
18
|
43
|
75.2
|
|
3
|
35
|
53.4
|
11
|
39
|
68.2
|
19
|
34
|
69.5
|
|
4
|
39
|
59.9
|
12
|
30
|
53.0
|
20
|
41
|
80.8
|
|
5
|
31
|
51.4
|
13
|
30
|
58.3
|
21
|
36
|
78.6
|
|
6
|
27
|
52.1
|
14
|
39
|
64.3
|
22
|
37
|
77.2
|
|
7
|
33
|
60.2
|
15
|
40
|
71.6
|
23
|
42
|
80.3
|
|
8
|
34
|
60.5
|
16
|
44
|
73.0
|
24
|
28
|
69.5
|
a. Compute the least-squares line for predicting yield (y) from temperature (x).
b. Plot the residuals versus the fitted values. Does the linear model seem appropriate? Explain.
c. Plot the residuals versus the order in which the observations were made. Is there a trend in the residuals over time? Does the linear model seem appropriate? Explain.