4/7 you pick someone with 1 sibling. 3/7 you pick someone with 2 siblings. If you pick a 1 sibling person, he has one sibling in the deck of 6 remaining people: 4/7 x 1/6 = 4/42 = 2/21 If you pick a 2 sibling person: 3/7 x 2/6 = 6/42 = 3/21 Add them: 5/21 says you get a sibling pair. 1 - 5/21 = 16/2...