Brain-Teaser 513: [Famiy tree]
From The Sunday Times, 11th April 1971 [link]
Damon Rigby is my grandfather, and his four children (including Henry) are all married. Aunt Fanny is the youngest and at her wedding to Charlie Jones last week I met four of my cousins; only two of our number have the same surnames and only one is married.
My mother’s name is Mary Rigby and I am her only child. My first name is that of the husband of my oldest aunt, but it is a tradition in our family that blood relations do not carry the same first name.
Aunt Fanny has a niece whose surname is Finch. Amanda has the same surname as Agatha’s sister. Aunt Doris has but a single daughter. Jack Prior has an aunt married to Tom whose niece is Amy Brown. The first name of Margaret’s father is the same as my father’s.
What are the full names of the five cousins?
This puzzle was originally published with no title.
[teaser513]
S2T2 
Jim Randell 8:33 am on 16 February 2020 Permalink |
I assumed a simple scenario with male/female marriages, and no couple having children from outside their marriages.
I wasn’t really sure on the best way to program a solution, so I started looking at bits I could simplify, and ended up with a complete manual solution. As follows:
There are four uncle/aunt pairs. And there are five cousins in total – the setter, plus the four cousins he met.
Assuming that Fanny and Charles don’t have any children. The setter is an only (male) child (of one of the other three uncle/aunt pairs). Another of the pairs has a single female child (Aunt Doris + husband). Which leaves the one remaining aunt/uncle pair with three offspring. Only one of the cousins is married, and only two share the same surname. So of these three one of them must be be a female, who married and changed her name. Leaving the other two unmarried and sharing the same family surname.
So this gives us the basic structure of the family tree:
Of the aunts/uncles generation there will be a (Henry) Rigby family, and a (Charlie) Jones family, and the remaining two families are from (Finch, Prior, Brown) with the unused one being the name of the married cousin.
The other two offspring of Damon (other than Henry and Fanny) must also be female (Doris and (not-Doris)) and have changed their names on marriage.
The setter must be the son of Henry Rigby and Mary (unknown), so he is (unknown) Rigby, sharing a name with the husband of Doris or (not-Doris).
So, with unknown values in brackets, we have the following 4 families:
Jack Prior must be one of the unmarried cousins in family [3], so the family name is Prior. He has an aunt married to Tom, this must be family [2], Doris Rigby (married to Tom (Finch or Brown)). Tom has a niece Amy Brown, so Amy Brown must be the married child in family [3], and parents of family [2] are Doris Rigby + Tom Finch.
Now, “the first name of Margaret’s father is the same as my father” (i.e. Henry). So Margaret can’t be the child in family [2] (as her father’s name is Tom), so she must be in family [3], and the father is Henry Prior.
The setter’s first name is the same as the husband of his eldest aunt, i.e. Tom Finch or Henry Prior, but the setter can’t be called Henry, as that is his father’s name, so the setter must be Tom Rigby.
Finally, “Amanda has the same surname as Agatha’s sister”. The child from family [2] does not have a sister, so Agatha must be the mother of family [3], and Agatha’s sister is Doris Finch, so Amanda Finch is her daughter.
Giving us the complete family tree of:
We don’t know the first name or the maiden name of the grandmother (Mrs Rigby), or the maiden name of Mary Rigby (the setter’s mother), or the first name of Amy’s husband (Mr Brown).
Solution: The five cousins are: Tom Rigby (the setter); Amanda Finch; Amy Brown, Jack Prior, Margaret Prior.
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