Paychecks and semester grades are delivered on a schedule of reinforcement. fixed-ratio fixed-interval variable-ratio variable-interval

The correct answer is fixed interval schedule of reinforcement

Fixed interval schedule of reinforcement refers to the process whereby rewards and reinforcement are provided only after a fixed amount of time has elapsed. When you are given your paycheck at the end of each month, you are motivated to work hard in anticipation of your paycheck. Similarly, if you know that you have end of semester exams coming up, you are motivated to put in effort in school to perform well in an exam get awarded with good grades. 

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.