What is the significance of a bell curve?

Answer 1

When you are graphing some quantity, in many cases you will wind up with a curve that is shaped like a bell, in other words, the graph gradually rises, then rises more sharply, then flattens out and declines in a symmetrical pattern, the same way that it rose. This reflects the fact that a great many things have a normal range, and so the quantity of that item peaks in the normal range and then declines as you get either more or less than the peak, and furthermore, the pattern does tend to form that distinctive bell shape. You could, for example, do a chart of the annual income of American families. Some have very high income, some have very low income, and most fall in the intermediate range. But you could do the same thing with endless numbers of other topics. If you were to capture pigeons and make accurate measurements of the lengths of their beaks, and then graph the results, you would get a bell curve. You could graph the weight of pet cats, or the cost of sweaters, or the age of houses, and so forth. Most things will produce some kind of bell curve.