(Đúng hay sai) P(B) = 0,8871

c)  Ta có: \({\rm{P}}\left( {{A_1}} \right) = 0,61;{\rm{P}}\left( {{A_2}} \right) = 0,39;{\rm{P}}\left( {B\mid {A_1}} \right) = 0,93;{\rm{P}}\left( {B\mid {A_2}} \right) = 0,82\).

Theo công thức xác suất toàn phần, ta có:

\({\rm{P}}\left( B \right) = {\rm{P}}\left( {{A_1}} \right){\rm{.P}}\left( {B\mid {A_1}} \right) + {\rm{P}}\left( {{A_2}} \right){\rm{.P}}\left( {B\mid {A_2}} \right) = 0,61.0,93 + 0,39.0,82 = 0,8871\).

Vậy c đúng