The variance ratio (VRn) can be used to determine whether returns satisfy the efficient market hypothesis (EMH). Let n = 5 and r5, be the five period log return at time t, where t = 1, 2, ..., T. 1. Express (15,t - 75) in terms of deviations of the relevant one period log returns from their respective means. Denote r; to be the mean of the five period log return