Normal Density Curve
The mean and standard deviation (std. dev.) characterize the normal density curve. The mean is the center point of the density curve. Below, three std. dev. to the left and to the right of the mean are marked on the graph axis. To change these parameters type in the desired value(s). By default the mean is set equal to 0 and the std. dev. is set equal to 1 (i.e., "Standard Normal Density"). The applet calculates the area shaded (red or green) under the curve. To find the proportion of values less than a given value, click the checkbox next to "Values Less than Endpoint". Similiarly, to find the proportion of values greater than a given value, click the checkbox next to "Values Greater than Endpoint". For the proportion between two values, click the checkbox next to "Values Between Endpoints". Finally, to find the proportion in the tails outside an interval, click "Values Outside Endpoints". You may move the endpoint values by dragging the points on the sliders that appear.