To find the volume of the model, we can use the scale factor of 1:20.
Since the scale factor is 1:20, it means that every unit on the model represents 20 units in the actual pool.
Given that the volume of the actual pool is 400m³, we can divide it by 20 to find the volume of the model:
400m³ / 20 = 20m³
So, the volume of the model swimming pool is 20m³.