Founders State Bank developed a standard for teller staffing that provided for one teller to handle $15$ customers per hour. During June, the bank averaged $50$ customers per hour and had five tellers on duty at all times. $($Relief tellers filled in during lunch and rest breaks.$)$ The teller compensation cost is $$12$ per hour. The bank is open eight hours a day, and there were $21$ working days during June.

Required:

Calculate the teller efficiency variance during June expressed in terms of number of tellers and cost per hour.

Now assume that in June, during the $11$ A$.$M$.$ to $1$ P$.$M$.$ period every day, the bank served an average of $80$ customers per hour. During the other six hours of the day, an average of $40$ customers per hour were served.

Calculate a teller efficiency variance for the $11$ to $1$ period expressed in terms of number of tellers per hour and total cost for the month.

Calculate a teller efficiency variance for the other six hours of the day expressed in terms of number of tellers per hour and total cost for the month.