Question

Dr. David Smith lived 1/13 of his life as a child. He spent 4/39 of his life preparing for an outstanding

medical career. For 1/ 2 of his life, he was a successful surgeon in a famous children's hospital. Since his
retirement, he has lived 13 years on a comfortable pension. How old is he? (unrealistic answer))

Answer 1

40 14/25 years

Explanation:

Well, this certainly is fun.

First, to find the fraction of the doctor's life which 13 years represents, subtract the fractions from 1 (and in this case l stands for lifetime):

`13 = (1 - ((1)/(13) + (4)/(39) + (1)/(2)))(l)`

`13 = ((25)/(78))(l)`

So, multiply this equation by the reciprocal of 25/78 to isolate one of l:

`13((78)/(25)) = l`

`l = 40(14)/(25)` years