Let's take a look at the normal state of a person - who pays a little attention to their diet, sleep and fitness:
In this person, the EEG should show brain waves in the range of alpha and beta waves. These are almost 50:50 distributed over both hemispheres of the brain.
He appears outwardly mentally stable and capable of solving minor complex tasks.
Every now and then, a flash of inspiration or an intuitive decision even leads him to his goal more efficiently.