Q 49 John Smith has developed the following forecasting mode

Q 4-9 John Smith has developed the following forecasting model: Y = 36 + 4.3X1

where Y = Demand for K10 air conditioners

X1 = the outside temperature

(a) Forecast the demand for K10 when the temperature is 70°F.

(b) What is the demand for a temperature of 80°F?

(c) What is the demand for a temperature of 90°F?

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  Q 4-13 Students in a management science class have just received their grades on the first test. The instructor has provided information about the first test grades in some previous classes as well as the final average for the same students. Some of these grades have been sampled and are as follows:

Student

1

2

3

4

5

6

7

8

9

1st test grade

98

77

88

80

96

61

66

95

69

Final average

93

78

84

73

84

64

64

95

76

(a) Develop a regression model that could be used to predict the final average in the course based on the first test grade.

(b) Predict the final average of a student who made an 83 on the first test.

(c) Give the values of r and r2 for this model. Interpret the value of r2 in the context of this problem.

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Q 4-14 Using the data in Problem 4-13, test to see if there is a statistically significant relationship between the

grade on the first test and the final average at the 0.05 level of significance. Use the formulas in this

chapter and Appendix D.

Student	1	2	3	4	5	6	7	8	9
1st test grade	98	77	88	80	96	61	66	95	69
Final average	93	78	84	73	84	64	64	95	76

Solution

4-9

(a)

y=36+4.3 (70)
y=36+ 301
y=337
So that would be 337 air conditioners

(b)

y=36+4.3 (80)
y=36+ 344
y=380
So that would be 380 air conditioners

(c)

y=36+4.3 (90)
y=36+ 387
y=423
So that would be 423 air conditioners