Re: probabilty

Posted by duck on Jun 06, 2013; 5:27pm
URL: http://discussion-forum.276.s1.nabble.com/probabilty-tp7581620p7581854.html

Hey Ayushya.. :)
As Sumit pointed out:
E(X) = 1*1/2+2*(1/2)^2+3*(1/2)^3+........   (I)
Mulitply both the sides by 1/2, you'll get:
1/2E(X)= 1*(1/2)^2+2*(1/2)^3+..............   (II)
Subtracting (II) from (I), you'll get:

1/2E(X) = 1/2+(1/2)^2+(1/2)^3+....
Therefore. E(X) =2.