Fifty people are asked which of football FFF, golf G G\,G and hockey H H\,H they watch. Five watch all three; 8 watch football and golf; 7 watch golf and hockey; 9 watch football and hockey. The totals watching football, golf and hockey are 31, 13 and 17 respectively. Pairwise totals include those who watch all three.
Find the number who watch football but not hockey.
Given that a person watches football, find the probability that they do not watch hockey.