What is the distance from F3 to Fz if the measurement from F7 to F3 is 6 cm?

To determine the distance from F3 to Fz based on the given information, we first need to recognize the layout of the electrode positions in the international 10-20 system for EEG placement.

If the measurement from F7 to F3 is 6 cm, this distance can serve as a reference. In the standard electrode placement system, the distance between various points is typically consistent throughout the layout. Fz is located along the midline of the head, which means that from F3 to Fz would typically be a direct distance in line with established proportions utilized in EEG placements.

Given that the distance from F7 to F3 is already determined as 6 cm, and considering the symmetrical nature of the EEG electrode arrangement, the distance from F3 to Fz also reflects an established segment of the overall layout. Therefore, the distance from F3 to Fz, being on a direct vertical line upward to the midline, will remain consistent with the established distances in this mapping, confirming it as 6 cm.

Hence, the correct answer is that the distance from F3 to Fz is 6.0 cm. This is validated by the proportionality of the distances within the EEG electrode positioning system.