Aptitude
Important notes and formula
If the current age of a person is X then N years hence (in future) his age will be (X+N).
Example:
In the year 2016 Salman was 16 years old. What will be his age in the year 2021?
N = 2021 - 2016
= 5 years
So, Salman's age 5 years hence will be (16 + 5) = 21.
If the current age of a person is X then N years ago (in past) his age was (X-N).
Example:
In the year 2010 Salman was 10 years old. What was his age in the year 2005?
N = 2010 - 2005
= 5 years
So, Salman's age 5 years ago was (10 - 5) = 5.
If the current age of a person A is X and person B is N times the age of person A. Then age of person B = NX.
Example:
If the current age of Rocky is 12 years and his older brother Jimmy is 1.5 times older than him. Find the age of Jimmy.
Current age of Rocky X = 12
N = 1.5
Age of Jimmy = NX
= 1.5 x 12
= 18 years.
If the current age of a person A is X and person B is 1/N times the age of person A. Then age of person B = X/N.
Example:
If the current age of Rocky is 12 years and his younger brother Johnny is 1/2 times Rocky. Find the age of Johnny.
Current age of Rocky X = 12
1/N = 1/2
Age of Johnny = X/N = 12/2
= 6 years.
If two ages are in the ratio M : N then we can write them as Mx and Nx.