Question 5081
This is sort of like a weighted mean.  Multiply number of beards time length of beard, sum the products, and divide by the number of men with beards.  I get this:

{{{(10*8 + 6*10 + 4 * 12 )/20}}}

{{{(80+60+48)/20 }}}
{{{188/20}}} = 9.4 inches


R^2 at SCC