Calculate the number average molecular weight M, and the weight average molecular weight M, for a sample of polystyrene with the following composition (where i is the degree of polymerization and the % is by weight). Further, calculate the variance of the number distribution of molecular weights (0) and the variance of the weight distribution molecular weights (ow). i 20 25 30 35 40 45 50 60 80 Weight % 30 20 15 11 8 6 4 3 3