Question

Ram is three times as old as his son Tenali. Five years later, Ram shall be two and a half times as old as Tenali.
The present age of Tenali is
A.20
B.15
C.25
D.24

Answer 1

Hint: At first we will assume the present age of Tenali to be x and using this and the given statement that Ram is three times as old as his son Tenali, we will get the age of Ram also. Now we have one more condition that five years later, Ram shall be two and a half times as old as Tenali.
Therefore using this we will get an equation and on solving that equation we will get the present age of Tenali.

Complete step-by-step answer:
Given data:present age of Ram $ = 3 \times $ [present age Tenali]
Age of Ram after 5 years $ = 2.5 \times $ [Age of Tenali after 5 years]
Let the present age of Tenali is x years
It is given that, the present age of Ram $ = 3 \times $ [present age Tenali]
So, the present age of Ram $ = 3x$
Therefore the age of Ram after 5 years $ = 3x + 5$
And the age of Tenali after 5 years $ = x + 5$
Now it is given that, Age of Ram after 5 years $ = 2.5 \times $ [Age of Tenali after 5 years]
i.e. $3x + 5 = 2.5(x + 5)$
On multiplication and simplification we get,
  $ \Rightarrow 3x + 5 = 2.5x + 12.5$
On Solving for the like terms, we get,
  $ \Rightarrow 0.5x = 7.5$
On Multiplying both sides by 2, we get,
  $ \Rightarrow x = 15$
Therefore, the present age of Tenali is 15 years
Option(B) is correct.

Note: Most of the students gets confused while writing the equation that with whose age we should multiply the factor, we can clear this confusion with our common sense the age of the father must be greater than the son so we should multiply the factor(if greater than 1) with the age of child as his age can possibly be equal to his father’s age after some addition or multiplication as an increment.