Comments on: Brain Teaser – How long did Christopher live?

By: Mike Sprayberry

Mike Sprayberry — Mon, 06 Jul 2009 19:14:48 +0000

Yeah, what they said! Pretty straightforward linear equation.

By: admin

admin — Sat, 04 Jul 2009 15:16:29 +0000

Thanks for that explanation.
Ken.

By: admin

admin — Sat, 04 Jul 2009 15:12:26 +0000

Good job.

By: Govinda Ram KC

Govinda Ram KC — Fri, 03 Jul 2009 21:48:56 +0000

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.

By: Allan Ropski

Allan Ropski — Fri, 03 Jul 2009 19:28:01 +0000

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.

By: KevinM in Woodbridge

KevinM in Woodbridge — Fri, 03 Jul 2009 19:08:46 +0000

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.

By: Tim

Tim — Tue, 30 Jun 2009 14:34:58 +0000

not sure, but quickly…

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

By: Robert L Queathem

Robert L Queathem — Mon, 29 Jun 2009 17:07:56 +0000

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