A natural number x is chosen at random from the first 100 natural numbers. The probability that $x+\frac{4}{x}>50$ is

Given $x+\frac{4}{x}>50\Rightarrow x^2+4>50x$
$\begin{array}{l}{x}^2-50x+625>625-4\\ \Rightarrow (x-25{)}^2>621\Rightarrow |x-25|>\sqrt{621}\Rightarrow x-25<-\sqrt{621}\\ \text{ Or }x-25>\sqrt{621}\Rightarrow x<25-\sqrt{621}\text{ Or }x>25+\sqrt{621}\\ \Rightarrow x<25-24.91\mathrm{Or}x>25+24.91\Rightarrow x=50,51,52,\dots .,100\end{array}$