The following table lists molecular weight data for a polypropylene material.

$\backslash$table$[[\backslash$table$[[$Molecular Weight$],[$Range $($g$/$mol$)]],x_i,w_i$

Find:

a$)$ the number$-$average molecular weight,

b$)$ the weight$-$average molecular weight

c$)$ the degree of polymerization