Question

A man in $1900s$ realised that in the year $1980$ his age was the square root of the year of his birth. What is his birth year?

• A. $1929$
• B. $1949$
• C. $1936$
• D. $1946$

Answer 1

Answer: (C)

$1936$

Let his birth year be $x$.
Hence
$1980-x=\sqrt{x}$
Let $\sqrt{x}=y$
$\therefore y^2+y-1980=0$
$\therefore y=44,-45$
Hence
$\sqrt{x}=44$
$x={44}^2=1936$