Need help with 7iib) :-(
Considering when they are part of the group, the number of combinations can be defined as 5C3, as there are 3 spots left (two have been taken by Jill and Jo).
The number of combinations when they aren't in a group is 5C5. Therefore the probability is 5C3/(5C3 * 5C5). This comes out to 10/11.