# Probability of getting positive integral roots of the equation $x^2-n=0$ for the integer $n \: \: \: 1 \leq n \leq 40$ is

$\begin {array} {1 1} (A)\;\large\frac{1}{5} & \quad (B)\;\large\frac{1}{10} \\ (C)\;\large\frac{3}{20} & \quad (D)\;\large\frac{1}{20} \end {array}$

Given
$x^2=n=0$
$x = \pm \sqrt n$
$n = 1,4,9,16,25,36$
$\therefore$ Required probability = $\large\frac{6}{40}$
$\large\frac{3}{20}$
Ans : (C)