Re: JNU !

Posted by a.m on May 14, 2012; 2:34am
URL: http://discussion-forum.276.s1.nabble.com/JNU-tp7552795p7555671.html

@ Sweta :

We know that var(X) = E(X)^2 - [E(X)]^2
putting the values we get,  4 = 16 - [E(X)]^2
and thus, [E(X)]^2= 16-4 = 12
and E(X)= sqrt 12 = 2*sqr root3

now var(2+3X)= 9* var(x) = 9*4 = 36
and E(2+3X) = 2+3 E(X) = 2+  3*2*sqrt 3
and thus [E(X)]^2 = 4+108+41.52 = 153. 53

and now v(2+3X) = 36
E(2+3X)^2- [E(2+3X)]^2 = 36
E(2+3x)^2 = 36 + 153.52 = 189.52


thus, none of the above. Hope you get it now.