Chemical analysis of a polymer sample shows that it is composed of fractions of molecules with different molecular weights (MW) as given in the table below. Based on this information, compute the number average molecular weight, Mn, and weight average molecular weight, Mw, for this polymer. What is the polydispersity index?

Fraction 1 nmn n 00 2 3 4 5 Weight fraction 0.1 0.19 0.24 0.18 0.11 0.08 0.06 0.04 MW (g/mol) 24,000 42,000 70,000 98,000 146,000 204,000 244,000 292,000 6 7 8