The following table lists molecular weight data for a polypropylene material

The following table lists molecular weight data for a polypropylene material.
Compute,
a) the number-average molecular weight
b) the weight-average molecular weight
c) the degree of polymerization.

Molecular Weight Range (g/mol) xi wi
8,000-16,000 0.05 0.02
16,000-24,000 0.16 0.10
24,000-32,000 0.24 0.20
32,000-40,000 0.28 0.30
40,000-48,000 0.20 0.27
48,000-56,000 0.07 0.1