What are some commonly known facts that are too bizarre for you to believe to be true?
For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some 'organic element' since I couldn't accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
Suppose a small bank has only one teller. Customers take an average of 10 minutes to serve and they arrive at the rate of 5.8 per hour. With only one teller, customers will have to wait nearly five hours on average before they are served. If you add a second teller the average wait becomes 3 minutes.