Results of Challenge #33

We received over 200 responses to this challenge, with numerous replies and reasons offered! I have included one from Jonah Sinick, who will tease your reasoning with his argument! Good replies to all who ventured into the logic!!!



Challenge #33: The Coffeehouse Family Reunion

Maggie has arranged a fun family reunion to be held at the Coffeehouse, in a private back room, small but comfortable. "Who's coming the the reunion?," asked Charles. With a crafty smile, Maggie replied: "One grandfather, one grandmother, two fathers, two mothers, four children, three grandchildren, one brother, two sisters, two sons, two daughters, one father-in-law, one mother-in-law, and one daughter-in-law. But don't worry about the small space in the back room, for not as many people will attend as it sounds. By the way, Charles, how many people will there be, and who will they be?"

Puzzled indeed, Charles hesitates, and asks you, his patrons, for some help. Provide you reasoned answer below, as you help out our poor, baffled Charles!

Describe who is coming, and how many there will be.


Below is the result of your feedback form.  It was submitted by
Jonah Sinick ( on Friday, November 23, 2001 at 03:47:22


city: San Francisco

state: CA

country: USA

comments: Seven People will be coming. First, there must be the grandparents, who fufill the requirement for grandmother and grandfather, as well as each being one of the two fathers/mothers. Therefore, there must one additional father and one additional mother after counting the grandparents. We know that there are four children total, and three grandchildren total. This implies that of the four children, only one can be a nongrandchild child. This child would be the grandparents only direct child. In determining the sex of this child, we need to look further down in the problem. We know that there are two sisters and one brother. Obviously, the grandparents and parents are not siblings of one another. Therefore, we have to look down to the three grandchildren. Of the three grandchildren, two could be sisters, and the other could be a brother. If this is so, the two daugther requirement is taken care of, and one of the two sons is also accounted for. At this point in the pict!
ure we have a grandmother, a grandfather, an unknown link, two grandsons and a grand daughter. The grandparents must have a son, otherwise there would not be two sons total. We also know that there is a daughter in law, and the child of the grandparents needs a wife with who to have the three grandchildren. Therefore, the son of the grandparents is married to a woman who serves as a mother, and daughter in law. We now have seven people, a grandfather, a grandmother, the son of the grandparents, his wife, and the three children of the son of the grandparents and his wife, two of whom are daughters. They fufill the requirements set in Maggie's list in the following manner:
(numbers are arbitrary placed on individuals to show when a person is the same person)
Grandfather: 1
Grandmother: 2
Fathers: 1 and 3
Mothers: 2 and 4
Children: 3, 5, 6, 7
Grandchildren: 5, 6, 7
Sons: 3, 7
Daughters: 5, 6
Sisters: 5, 6
Father in Law: 1
Mother in Law: 2
Daughter in Law: 4

Seven total people