Consider that
[tex] 0.4 = \dfrac{4}[10} = \dfrac{2}{5} [/tex]
This means that a sport has a 0.4 chance of being sold out if 2 out of 5 events are sold out.
Rugby 7s has 3 out of 5 events sold out
Juntior athletics has 3 out of 5 events sold out
Volleyball has 2 out of 5 events sold out, so this is the sport you're looking for.
As for the second question, rugby and athletics are both sold out on two events (events 1 and 5). So, again, the chance is of 2 out of 5 events, which leads to a probability of [tex] \frac{2}{5} [/tex]