Answer:
4.15 spikes/sec
Explanation:
Given that neurons fire action potentials (spikes) at different frequencies under different circumstances. In one study, researchers position an awake-behaving monkey so that he or she is looking at a luminous dot 40 cm away, and they record the activity of a single neuron in the monkey's brain to determine the neuron's baseline.
Sample size n = 64

Standard error of sample = std dev / sqrt n
=

Hence standard error of sample mean for the sample with size 64 is
4.15 spikes per second