Statistical variables such as length, weight, volume etc. are ofthen normally distributed. The shape of the normal curve is determined by the mean and the standard deviation of the distribution. The formula for the normal distribution has been programmed into your graphing calculator so that it can draw a normal curve for you if you enter values for those variables.
The corresponding normal probabilities can be found by calculating the required area under the normal curve. In the applet
you see :
The graphing calculator can directly calculate these probabilities. It will also shade the corresponding area for you.