你好,A股票标准差=[(26%-22.45%)2×10%+(11%-22.45%)2×10%+(15%-22.45%)2×20%+(27%-22.45%)2×25%+(21%-22.45%)2×20%+(32%-22.45%)2×15%](1/2)=0.0669
B股票标准差=[(13%-28.25%)2×10%+(21%-28.25%)2×10%+(27%-28.25%)2×20%+(41%-28.25%)2×25%+(22%-28.25%)2×20%+(32%-28.25%)2×15%](1/2)=0.0891