A theater sells its reserved seats for $50 and on average sells 40 reserved seats per show. It has calculated that for every $1 it reduces the price of a reserved seat, it sells 2 additional reserved seats. If it wants to maximize its revenue from the sale of reserved seats, at what price should it sell its tickets?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters