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Brain Teaser – How long did Christopher live?

Christopher’s youth lasted 1/6 of his life. He had his first beard in the next 1/12 of his life. At the end of the following 1/7 of his life Christopher got married. Five years from then his son was born. His son lived exactly 1/2 of Christopher’s life. Christopher died 4 years after the death of his son. How long did Christopher live?

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8 comments

  1. Mike Sprayberry

    Yeah, what they said! Pretty straightforward linear equation.

  2. 84 Years. Son’s life is then 42 years.

    After 1/6 (14 years) + 1/12(7 years) + 1/7(12 years) = 33 Years old, gets married.

    5 Years later son is born – 38 Years.

    Plus son’s like; 38+42 = 80 Years.

    4 Years later Christopher dies at 84 years old.

    • Govinda Ram KC

      Allan is right. Christopher’s life is 84 years. His son’s life is 42 years, as given in the question. The following mathematical explanation justifies the answer:
      Suppose, life of Christopher = L,
      Life of son = S.
      S= L/2 ………………..eq 1
      1/6 L (youth) + 1/12 L (beard appearance) + 1/7 L (marriage) + 5 yrs (son’s birth) + S (life of son) + 4 yrs (Christopher’s death) = L (Christopher’s life)
      1/6 L + 1/12 L +1/7 L + 5 + S + 4 = L ……………eq 2
      By solving these 2 simple equations, we get L = 84 and S = 42.
      Hence, Christopher’s life is 84 years.

  3. KevinM in Woodbridge

    Christopher was 84 when he died.

    14 yrs of youth (1/6 of 84)
    7 yrs to grow beard (1/2 of 84)
    12 yrs before marriage (1/7 of 84)
    5 yrs before child is born
    42 yrs child lives (1/2 of 84)
    4 yrs to death.

    1/6x + 1/12x + 1/7x + 1/2x + (4 + 5) = x (life span)

    Of course, as a father, I never like to see parents outlive the children. Make it fish next time. 😉

  4. not sure, but quickly…

    1/6x + 1/12x + 1/7x + 5 + 1/2x + 4 = x
    x = 84, son = 42?

  5. Robert L Queathem

    84 years … Life = youth (L/6) + beard (L/12) + single (L/7) + birth (5) + son’s life (L/2) + after son’s death (4) … L = [(14 + 7 + 12 + 42) / 84] x Life +9 … 9 = [(14 + 7 + 12 + 42 – 84) / 84] x Life … 9 = 9/84 Life … Life = 84

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