2.设X~N(1,22),求下列概率: (1)P(X<2.2);(2)P(1.6≤X<58); (3)P(Xk35);(4)P(X|4.56) 2.2-1 解(1)P(X<2.2)=①()=①(0.6)=0.7527 2 5.8 (2)P(-16≤X<58)=Φ( 1.6 )-①( 2 2 =Φ(24)-(-13)=①(24)-1+Φ(13)=08950 3.5-1 (3)f(Xk3.5)=@2 3.5 =Φ(125)-Φ(-225)=Φ(1.25)-1+Φ(225) (4)P(X4.56)=1-P(X4.56 4.56 4.56-1 =1-① +Φ( =0.04029 2. 解 (1) P(X 2.2) ) 2 2.2 1 ( (0.6) 0.7527 (2) P(1.6 X 5.8) ) 2 5.8 1 ( ) 2 1.6 1 ( (2.4) (1.3) (2.4) 1 (1.3) 0.8950 (3) P(| X | 3.5) ) 2 3.5 1 ( ) 2 3.5 1 ( (1.25) (2.25) (1.25) 1 (2.25) (4) P(| X | 4.56) 1 P(| X | 4.56) ) 2 4.56 1 1 ( ) 2 4.56 1 ( 0.0402