Question

Four years ago the average age of $A,B$ and $C$ was $25$ years. Five years ago the average age of $B$ and $C$ was $20$ years. $A$'s present age is

• A. $60$ years
• B. $37$ years
• C. $62$ years
• D. $15$ years

Answer 1

The correct option is B $37$ years

Let the present ages of $A,B,C$ be $x,y$ and $z$ years respectively.
Given, $\frac{(x-4)+(y-4)+(z-4)}{3}=25$

$\Rightarrow x+y+z-12=75$

$\Rightarrow x+y+z=87$ .....(1) and

$\frac{(y-5)+(z-5)}{2}=20$

$\Rightarrow y+z-10=40$

$\Rightarrow y+z=50$ ....(2)
From equations (1) and (2), we have
$A$'s age $=x=(x+y+z)-(y+z)=(87-50)$ years $=37$ years