Brain Teasers
Ages Ago My Age ...
My friend Rupesh said to me: "Five years ago, the sum of my age and my son's age was a third of five times the average of the present ages of my son and myself." If the son will be 15 years old in 5 years time, how old is Rupesh now?
Answer
Rupesh's present age is 50 years.Let the ages of Rupesh and his son 5 years ago be R and S respectively.
The from the statement of Rupesh which states that "Five years ago, the sum of my age and my son's age was a third of five times the average of the present ages of my son and myself.", we can write
R+S = (1/3)*(5)*(R+5+S+5)/2
R+S = (5/3)* (R+S+10)/2
R+S = (5/6)*(R+S+10)
It is also given in the problem that the son will be 15 years old in 5 years time
i.e., S+10 = 15. or S = 5 years.
Substituting the value of S in the above equation we get,
R+5 = (5/6)*(R+5+10)
R+5 = (5/6)*(R+15)
6R+30 = 5R+75
R = 45 years.
This was Rupesh's age 5 years ago.
Hence his age today is 45 + 5
= 50 years.
Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments hidden to avoid spoilers.
Follow Braingle!