Normal distributions are symmetric around their mean. The mean, median, and mode of a normal distribution are equal. The area under the normal curve is equal to 1.0 1.0. Normal distributions are denser in the center and less dense in the tails. Normal distributions are defined by two parameters, the mean (μ μ) and the standard deviation (σ σ ). A normal distribution, sometimes called the bell curve (or De Moivre distribution [1]), is a distribution that occurs naturally in many situations. For example, the bell curve is seen in tests like the SAT and GRE. The normal distribution model always describes a symmetric, unimodal, bell shaped curve. However, these curves can look different depending on the details of the model. Specifically, the normal distribution model can be adjusted using two parameters: mean and standard deviation. The normal distribution is an important probability distribution used in statistics. Many real world examples of data are normally distributed. Normal Distribution The normal distribution is described by the mean ( μ) and the standard deviation ( σ ). The normal distribution is often referred to as a 'bell curve' because of it's shape: Properties of the Normal Distribution The Empirical Rule. For all normal distributions, 68.2% of the observations will appear within plus or minus one Skewness. Skewness measures the degree of symmetry of a distribution. The normal distribution is symmetric and has a Kurtosis. Kurtosis A normal distribution is the continuous probability distribution with a probability density function that gives you a symmetrical bell curve. Simply put, it is a plot of the probability function of a variable that has maximum data concentrated around one point and a few points taper off symmetrically towards two opposite ends. The normal distributions are closely associated with many things such as: Marks scored on the test Heights of different persons Size of objects produced by the machine Blood pressure and so on. Normal distributions come up time and time again in statistics. A normal distribution has some interesting properties: it has a bell shape, the mean and median are equal, and 68% of the data falls within 1 standard deviation. What is a normal distribution? ues9G.