FIGURE A.5 The Standard Normal Curve The standard normal curve has several characteristics. Most apparent is its symmetrical bell shape. On such a curve, the mean, the median, and the mode all fall at the same point. But not every curve that is shaped roughly like a bell is a standard normal curve. With a normal curve, specific percentages of the distribution fall within each standard deviation unit from the mean. These percentages are shown on the graph. (Because of rounding, percentages add up to more than 100%.)