In a random walk, suppose I toss an unbiased coin and if it lands head, I get £1, tails £-1.
Let R(i) denote the amount I get in the ith toss.
I have read E(R(i)) = 0, E((R(i))^2) = 0 and E(R(i)R(j)) = 0
I can understand how E(R(i)) = 0 because it's 0.5 * (1) + 0.5 (-1)
What about the other two?
Any help is appreciated.