8) Of the 25 that like football, 10 like hockey as well so only 2 like hockey but not football, and 15 like football but not hockey. So we have 15+10+2=27 students out of 40 that like football or hockey or both. Also, 15+2=17 like football or hockey, but not both, so the probability (a) of selecting a student who likes one or the other (but not both) is 17/40=0.425 or 42.5%.
(b) 50-27=23 students like neither game, so that's 23/40=0.575 or 57.5% (this is 1 or 100%-(a)).
(c) Venn diagram:
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