Ch 解(1)令f(x)x=「 1000 2dx=1 =1000 (2)P(X≤17001500<X<2000 =x0005020 =P(1500<Xs1700/P1500<X<200 7001000 2000 1000 d x d x 1500 500 X /124 ≈04706 51/651Ch2 -56 解 (1) 令 ( ) d d 1 1000 2 = =   + + − x xc f x x c = 1000 P ( X 1700 1500  X  2000 ) (2) = P ( X 1700,1500  X  2000 ) P (1500  X  2000 ) = P (1500  X 1700 ) P (1500  X  2000 )  = 1700 1500 2 d 1000 x x  2000 1500 2 d 1000 x x 514 = 61 0.4706 . 51 24 = 