The actual distance is $150 \, \text{cm}$.

To determine the actual distance from a scaled drawing, it is essential to understand the scale ratio. In this scenario, the scale is $1:50$, which indicates that $1 \, \text{cm}$ on the drawing corresponds to $50 \, \text{cm}$ in real life. To calculate the actual distance, you multiply the measurement from the drawing by the scale factor. Here, the length of the drawing is $3 \, \text{cm}$. Therefore, the calculation is as follows:

This method is widely applicable in various fields such as architecture, engineering, and geography, where scaled drawings are frequently utilized. By applying the scale ratio, you can efficiently convert measurements from the drawing into real-world dimensions.

Keep in mind that the scale ratio indicates how many units of actual distance are represented by one unit on the drawing. In this example, each $1 \, \text{cm}$ on the drawing equals $50 \, \text{cm}$ in reality, making it easy to calculate the actual size of objects or distances.