题目

If children aren’t particularly interested in history, it’s not their fault. History, while potentially an exciting subject, hasn’t traditionally been treated as interesting a subject as math and reading. They are often given only a glimpse into a historical events or customs into context, so it’s no wonder children don’t often think of history as a subject that excites them and makes them know more. But it doesn’t have to be this way. History has the power to come alive if it’s just presented to children in the right way. I was reminded of this when I took my daughter and某84消毒液工厂，去年五月份以前，每天的产量与销售量均为500箱，进入五月份后，每天的产量保持不变，市场需求量不断增加.如图是五月前后一段时期库存量(箱)与生产时间(月份)之间的函数图象.（五月份以30天计算）（1）该厂   月份开始出现供不应求的现象，五月份的平均日销售量为    箱？（2）为满足市场需求，该厂打算在投资不超过220万元的情况下，购买8台新设备，使扩大生产规模后的日产量不低于五月份的平均日销售量.现有A、B两种型号的设备可供选择，其价格与两种设备的日产量如下表：型   号AB价格（万元/台）2825日产量（箱/台）5040 请设计一种购买设备的方案，使得日产量最大；（3）在（2）的条件下（市场日平均需求量与5月相同），若安装设备需5天（6月6日新设备开始生产），指出何时开始该厂有库存？