3. (5 points) During an earthquake, the epicenter simultaneously sends out longitudinal waves and transverse waves, with propagation speeds of 5.94 km/s and 3.87 km/s, respectively. In a certain earthquake, the seismograph at a monitoring station received the longitudinal waves 11.5 seconds before receiving the transverse waves from the same earthquake. The distance from the epicenter to the monitoring station is $\qquad$ kilometers. (Round the answer to the nearest integer)
【Solution】Solution: Let the distance from the epicenter of this earthquake to the seismic monitoring station be $s \, \text{km}$. According to the problem,
$$
\begin{array}{c}
\frac{s}{3.87}-\frac{s}{5.94}=11.5, \\
\frac{5.94-3.87}{3.87 \times 5.94} s=11.5, \\
s=127.7777 \\
127.7777 \text{ km} \approx 128 \text{ (km). }
\end{array}
$$

Answer: The distance from the epicenter of this earthquake to the seismic monitoring station is approximately $128 \, \text{km}$. Therefore, the answer is: 128.