機率與統計

A. (f(2),f(3),f(4),f(5),f(6),f(7),f(8),f(9),f(10),f(11),f(12))
=(1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1)/36

B. P(2<=x<=4)=f(2)+f(3)+f(4)=(1+2+3)/36= 1/6

C. E(x)=(2*1+3*2+4*3+5*4+6*5+7*6+8*5+9*4+10*3+11*2+12*1)/36=7
method2=(1+2+3+4+5+6)/6 * 2= 7

D. V(x)=E(x^2)-[E(x)]^2
=(4*1+9*2+16*3+25*4+36*5+49*6+64*5+81*4+100*3+121*2+144*1)/36-7^2
=35/6
method2=2*[(1^2+2^2+3^2+4^2+5^2+6^2)/6- (7/2)^2]= 35/6