Your weighted average can be calculated quite easily, using a formula field coded as:
{=(B2*C2+ B3*C3+ B4*C4+ B5*C5+ B6*C6+ B7*C7+ B8*C8+ B9*C9+ B10*C10+ B11*C11+ B12*C12+ B13*C13)*100/B14 \# 0.00%}
To see how to do a wide range of calculations in Word, check out my
Microsoft Word Field Maths Tutorial:
https://www.msofficeforums.com/word/...-tutorial.html
Note: The field brace pairs (i.e. '{ }') for the above example are created in the document itself, via Ctrl-F9 (Cmd-F9 on a Mac) or via Insert|Quick Parts>Field>=(Formula); you can't simply type them or copy & paste them from this message.