In tratification with two trata, the value of the Wh and Sh are given a follow. Computed , a) tandard error of total mean i tobe 0. 1 and toptal ample ize n=n1n2 to be minimized? b) the tandard error of the etimated mean of each tratum i to be 0. 1? c) the tandard error of bthe difference between the two etimated tratum mean i to be 0. 1?