a) Retornos observados

a1) retorno médio observado para cada um dos ativos
_Microsoft = (74,17 + 122,00 + 15,09 – 5,43 + 51,29 + 43,59 + 88,33 + 56,39 + 114,61)/9
_Microsoft = 62,23%
_KM = (- 3,17 + 30,57 + 7,58 + 10,36 + 2,55 + 37,57 + 22,68 + 33,10 + 28,32)/9
_KM =18,84%

a2) variância dos retornos observados

Microsoft:
= {[(74,17 – 62,23)² + (122,0 – 62,23)² +(15,09 – 62,23)² +(-5,43 – 62,23)² +(51,29 – 62,23)² + (43,59 – 62,23)² + (88,33 – 62,23)² + (56,39 – 62,23)² + (114,61 – 62,23)²/(9 - 1)}/10.000
= 0,180516

Mercado:
= {[(-3,17 –18,84 )² +(30,57 –18,84)² +(7,58 –18,84)² +(10,36 –18,84)² + (2,55 – 18,84)² + (37,57 –18,84)² + (22,68 – 18,84)² + (33,10– 18,84)² + (28,32 – 18,84)²]/(9 - 1)}/10.000
= 0,021811

b) covariância entre os retornos observados da Atlanta e do mercado

Cov_Km,Microsoft = {[(74,17 – 62,23) (-3,17 – 18,84) + (122,0 – 62,23) (30,57 –18,84 ) + (15,09 – 62,23) (7,58 – 18,84) + (-5,43 – 62,23) (10,36 – 18,84) + (51,29 – 62,23) (2,55 – 18,84) + (43,59 – 62,23) (37,57 – 18,84) + (88,33 – 62,23) (22,68 – 18,84) + (56,39 – 62,23) (33,10 – 18,84) + (114,61 – 62,23) (28,32 – 18,84)]/(9-1)}/10.000
Cov_Km,Microsoft = 0,023566

c) beta da Microsoft

ß_Microsoft= 0,023566/0,021811
ß_Microsoft = 1,08