A Family of Puzzles
By David Beagan
This is a classic. Hopefully, those who have heard it may enjoy it again. A man is holding a picture of someone and while looking at it proclaims, “Brothers and sisters I have none, but this man’s father is my father’s son.” Who is in the picture?
Boys and Girls
The Gardner family is composed of a mother, a father, and sons and daughters. Around the dinner table one day, one of the daughter’s says, “did you ever stop to think, I have three times as many brothers as I have sisters?” And one of the sons replies, “Yes but I have the same number of brothers as sisters.”
How many sons and daughters are in the Gardner family?
The part of the bird
that is not in the sky,
which can swim in the ocean
and always stay dry.
What is this?
Randy was frequently in trouble. He was brought in for questioning on a robbery. The detective on the case tells him, “We found your finger prints at the crime scene. This will be an open and shut case.”
Randy replies, “Perhaps you don’t know, I have an identical twin brother, Andy. We share the same DNA. How do you know it is not my twin brother’s fingerprints you found there? If this case goes to trial, there is reasonable doubt that those are my fingerprints that you found.”
The detective replies, “Well, you and your brother will have to submit to a DNA test to validate your claim.”
Randy walked out of the police station a free man. Later the detective called back and told Randy the DNA tests wouldn’t be necessary, and just then an officer knocked at the door. The detective explained that they would be arresting Randy and holding him for trial.
What did the detective find out?
In earlier times, it so happened that two brides and their jealous husbands, encounter a river. There is a small boat to get them across the river. The boat can carry just one or two people. The river crossings must be arranged so that no woman is left with a man unless her husband is also present. How many trips does it take to ferry them all across the river?
Cousin Hank and Little Hank were born on the same day of the year, but a number of years apart.
At today’s birthday celebration, Cousin Hank said, “I haven’t been able to attend all of Little Hank’s birthday parties, but I remember attending one where my age was exactly seven times as much as Little Hank’s age. At another celebration, I was four times older. At another I was three times older. And now today, I am just twice as old as little Hank. Little Hank is catching up to me!”
How old is Little Hank today?
The son of a professor’s father is talking to the father of the professor’s son. The professor does not take part in this conversation. How is this possible?
In the country of Alpha, the dictatorial government decrees that each couple must have children until they have a boy. Once they have a boy, then they must stop having children.
In the country of Beta, their government decrees that each couple must keep having children until they have one more boy than girl. Then they must stop having children.
Assume that the odds of having a boy or girl is the same with each individual birth. Would either of the strategies employed by Alpha or Beta be expected to result in more boys in the population?