$$10000=50\cdot2^\frac{x}{30\,\text{min}}~~~~~|:50$$
$$200=2^\frac{x}{30\,\text{min}}~~~~~|\ln$$
$$\ln 200=\frac{x}{30\,\text{min}}\ln 2~~~~~\left|\cdot\frac{30\,\text{min}}{\ln 2}\right.$$
$$ x= 30\,\text{min}\cdot\frac{\ln 200}{\ln 2} $$
\( x\approx 30\,\text{min}\cdot7.64385618977472469574063885897878 \approx 229.32\,\text{min} \approx 3\,\text h ~ 49\,\text{min}~18,9\,\text s \)