Sorry - I messed up explaining this :)
Here's how it works; If you have a set of options:
X x 3
Y x 3
Z x 2
then Hexroll will roll a d8 (3+3+2) on a table containing 3 Xs, 3 Ys and 2 Zs. So X has a 3 in 8 chance of being selected and Z has a 2 in 8 chance of being selected.