In this demo you can draw "regions of integration" D on the contour plot of $f_X(x)$ and see the corresponding volume on the surface plot. Choose a density and the shape of the brush in the selection bellow. The scroll bar changes the size of the brush.
| $f_{XY}(x,y)$ | Brush Size | Brush Shape |
| 10 |
|
$P(x \in D) = $ 0.0 |
$f_{XY}(x,y)$ |