The local grocery store receives a shipment of 50 cases of cat food every month. The inventory of cat food (i.e., the number of cases of catfood on hand as a function of days) is given by I(x) = 50 cos(⇡x/15) 60.

(a) What is the average daily inventory over a month?
(b) If the cost of storing a case is 2 cents a day, determine the average daily holding cost over the month.