3. A city's No. 10 Middle School has built a new six-story enclosed student dormitory, with 15 rooms on each floor, and this dormitory has only one entrance and exit safety door. The safety inspection department has tested the normal passage of this safety door: in an emergency, the safety door can function normally for the first $1 \mathrm{~min}$, but due to the continuous crowding of students, the exit efficiency will decrease by $10 \%$ in the second $1 \mathrm{~min}$, and the exit efficiency will be $20 \%$ lower than normal afterwards. To ensure that all students in the dormitory can evacuate safely within $5 \mathrm{~min}$ in an emergency, the school stipulates that each room can accommodate 8 people. Therefore, the safety inspection department measured that the minimum number of people that this safety door can normally pass through per minute should be $\qquad$ people.
3.168.

Assuming that under normal circumstances, this safety door can allow an average of $x$ people to pass through per minute. According to the problem, we have
$$
8 \times 15 \times 6 \leqslant x(1+90\%+80\% \times 3) .
$$

Solving this, we get $167.4 \approx \frac{720}{4.3} \leqslant x$.
Therefore, the minimum integer value of $x$ is 168.