A toothpaste factory had a problem... Due to the way the production line was set up, sometimes empty boxes were shipped without the tube inside. People with experience in designing production lines will tell you how difficult it is to have everything happen with timings so precise that every single unit coming off of it is perfect 100% of the time. Small variations in the environment (which cannot be controlled in a cost-effective fashion) mean quality assurance checks must be smartly distribute…