Question

TABLE 12-10 The management of a chain electronic store would like to develop a model for predicting the weekly sales (in thousand of dollars) for individual stores based on the number of customers who made purchases. A random sample of 12 stores yields the following results: Customers Sales (Thousands of Dollars) 907 11.20 926 11.05 713 8.21 741 9.21 780 9.42 898 10.08 510 6.73 529 7.02 460 6.12 872 9.52 650 7.53 603 7.25 True or False: Referring to Table 12-10, the mean weekly sales will increase by an estimated $0.01 for each additional purchasing customer Seleccione una Verdadero Falso

Answer 1

X	Y	XY	X²	Y²
907	11.2	10158.4	822649	125.44
926	11.05	10232.3	857476	122.1025
713	8.21	5853.73	508369	67.4041
741	9.21	6824.61	549081	84.8241
780	9.42	7347.6	608400	88.7364
898	10.08	9051.84	806404	101.6064
510	6.73	3432.3	260100	45.2929
529	7.02	3713.58	279841	49.2804
460	6.12	2815.2	211600	37.4544
872	9.52	8301.44	760384	90.6304
650	7.53	4894.5	422500	56.7009
603	7.25	4371.75	363609	52.5625

Ʃx =	8589
Ʃy =	103.34
Ʃxy =	76997.25
Ʃx² =	6450413
Ʃy² =	922.035
Sample size, n =	12
x̅ = Ʃx/n = 8589/12 =	715.75
y̅ = Ʃy/n = 103.34/12 =	8.611666667
SSxx = Ʃx² - (Ʃx)²/n = 6450413 - (8589)²/12 =	302836.25
SSyy = Ʃy² - (Ʃy)²/n = 922.035 - (103.34)²/12 =	32.10536667
SSxy = Ʃxy - (Ʃx)(Ʃy)/n = 76997.25 - (8589)(103.34)/12 =	3031.645

Slope, b = SSxy/SSxx = 3031.645/302836.25 =    0.01001
y-intercept, a = y̅ -b* x̅ = 8.61167 - (0.01001)*715.75 =    1.44641
Regression equation :   
ŷ = 1.4464 + (0.01) x  

Answer: True