If the measurement from T6 to Pz is 8 cm, what is the distance from P4 to Pz?

To determine the distance from P4 to Pz based on the measurement given from T6 to Pz, it is essential to understand the standard placements of the electrode sites on the scalp as outlined by the 10-20 system. In this system, T6 is located on the temporal area, while Pz is positioned on the parietal area towards the back of the head.

Since the distance from T6 to Pz is given as 8 cm, this represents a certain segment of the overall layout. P4, being located more laterally on the scalp in the parietal region, will have a distance to Pz that is less than the distance from T6 to Pz. The locations are organized such that P4 is situated approximately halfway between T6 and Pz due to the symmetry of the 10-20 system.

Thus, taking into consideration the standard distances typically observed in these measurements and the fact that the distance from T6 to Pz is 8 cm, P4 to Pz would indeed be about half of that distance, which results in 4 cm. This understanding of the electrode placements and their relative distances confirms that the correct answer is 4 cm.