Revisit Example 16-5. What are the degrees of polymerization for the weight average and number average molecular weights?

Example 16.5

We have a polyethylene sample containing 4000 chains with molecular weights  between 0 and 5000 g/mol, 8000 chains with molecular weights between 5000 and  10,000 g/mol, 7000 chains with molecular weights between 10,000 and 15,000 g/mol,  and 2000 chains with molecular weights between 15,000 and 20,000 g/mol. Determine  both the number and weight average molecular weights.