I want to know the answer to the following question:
Why should noise-based speed be rounded down to a lower standard?
All the background I'm provided with is that "If the noise-based speed (40:1) is lower than the saturation-based speed, or undefined because of high noise, the saturation-based speed is specified, rounded upwards to a standard value, because using the noise-based speed would lead to overexposed images.". Is that enough to answer the question?