<p>某厂生产某产品<img src="https://file.gaojiufeng.cn/learnAppQuestion/17/6c/176c676a5aed5a5b0a258c78093f0aba.jpg" style="width: 100%;height: auto;">吨时总成本为<img src="https://file.gaojiufeng.cn/learnAppQuestion/09/30/0930f46c49349e4e9ddfcade79fd2e0a.jpg" style="width: 100%;height: auto;"> （万元）. 问当产量<img src="https://file.gaojiufeng.cn/learnAppQuestion/17/6c/176c676a5aed5a5b0a258c78093f0aba.jpg" style="width: 100%;height: auto;">为多少时，产品的平均成本最低？</p>