Ventaz corp manufactures small windows for back yard sheds.​ historically, its demand has ranged from 30 to 50 windows per day with an average of 42. alex is the one production worker and he works eight hours a​ day, five days a week. each order is one window and each window takes 5 minutes. alex plans to add doors to its product line and anticipates that they will average 4 doors per day. each door takes 540 minutes to install. what is the average waiting​ time, in​ minutes, if alex continues to be the only​ worker?