A property manager wants to estimate the annual costs of window cleaning for a newly
acquired office building. She collected the following information related to costs of the 10
properties she currently manages:
xi=17,470 x2
i=34,125,100, where x is the window surface (ft2)
yi=1,350,955 y2
i=203,605,360,640 and xiyi=2,635,901,696, where y is the
cleaning costs
Determine a CER equation for the cleaning costs and the correlation coefficient.
x= ( xi)/n=1747; y= ( yi/n) =135,095.5
b1=2,635,901,696 – (1747)(1,350,955)
34,125,100 – (1747)(17,470)=76.500
b0=135,095.5 – (76.500)(1747)
=1450.000
y =1450.000 +76.500x
R =Sxy
SxxSyy; Sxy =2,635,901,696 – (17,470)(1,350,955)/10 =275,783,311.000
Sxx =34,125,100 –(17,470)2/10 =3,605,010.000
Syy =203,605,360,640 –(1,350,955)2/10 =21,097,419,437.500
Thus, R =275,783,311.000
(3,605,010.000)(21,097,419,437.500)
=1.0000