Mathematics is a useful tool to prove or disprove someone's claim. The excerpts clipped to this post came from an interesting article from Plus Magazine web site (i.e. Issue 49), which explains how Statistics is used to make sense of all the information we receive from different sources. I encourage you to read the article and become aware how mathematics can help you make informed decisions.
Have you recently sat down in a lovely restaurant, picked up the menu, and read
One reason for this fairly recent change in procedures is that restaurant owners
The model says that the tip rate decreases by a little under 1% for each