商务统计学(第四版)课后习题答案第十二章
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CHAPTER 12
12.1 (a) When X = 0, the estimated expected value of Y is 2.
(b) For each increase in the value X by 1 unit, you can expect an increase by an estimated 5 units in the value of Y .
(c) ˆ2525(3)17Y
X =+=+= 12.2 (a) yes, (b) no,
(c) no, (d) yes
12.3 (a) When X = 0, the estimated expected value of Y is 16.
(b) For each increase in the value X by 1 unit, you can expect a decrease in an estimated 0.5 units in the value of Y .
(c) 13)6(5.0165.016ˆ=-=-=X Y
12.4
(a)
(b) For each increase in shelf space of an additional foot, there is an expected increase in weekly sales of an estimated 0.074 hundreds of dollars, or $7.40. (c)
042.2)8(074.045.1074.045.1ˆ=+=+=X Y
, or $204.20
12.5
(a)
Scatter Diagram
050100150200250300350400
4500
100
200
300
400
500
600
700
X, Reported (thousands)
Y , A u d i t e d (t h o u s a n d s )
(b)
For each additional thousand units increase in reported newsstand sales, the mean audited sales will increase by an estimated 0.5719 thousand units.
(c)
()ˆ26.72400.5719400255.4788Y
=+= thousands.
12.6
(a)
(b) Partial Excel output:
Coefficients Standard Error t Stat P-value Intercept -2.3697 2.0733 -1.1430 0.2610 Feet 0.0501 0.0030 16.5223 0.0000
(c) The estimated mean amount of labor will increase by 0.05 hour for each additional cubic foot moved.
(d)
()ˆ 2.3697+0.050150022.6705Y
=-=
Scatter Diagram
010********
607080900
200
400
600
800
1000
1200
1400
1600
X
Y
12.7
(a)
(b) ˆ0.19120.0297Y
X =+ (c) For each increase of one additional pound, the estimated mean number of orders will increase by 29.7.
(d) ()ˆ0.19120.029750015.043Y
=+=thousands 12.8
(a)
Scatter Diagram
0100200300400500600700800900
50
100
150
200
250
X, Revenue (Millions of dollars)
Y , V a l u e (M i l l i o n s o f d o l l a r s )
(b)
0246.2599b =-, 1 4.1897b =
(c)
For each additional million dollars increase in revenue, the mean annual value will increase by an estimated 4.1897 million dollars. Since revenue cannot be 0, the Y intercept has no practical interpretation. Also, since the Y intercept is outside the range of the observed values of the X variable, its interpretation should be made cautiously.
(d)
()ˆ246.2599 4.1897150382.2005Y
=-+= million dollars.