Apple bruising in packing plant

This page both shows a graphical representation of the joint, marginal and conditional probabilities and also explains the relationship between them.

The area of each rectangle equals the joint proportion of an x-value and a y-value. Click on any rectangle — its height is P(y) and its width is P(x given y). Therefore

Joint propn   =   marginal propn times conditional propn

Click the box at the bottom right to alter the shape of the rectangles (but keep their areas the same). Now the width is P(x) and the height is P(y given x).

The data set is not real. The scenario is probabilities that apples of two types (Fuji and Granny Smiths) are bruised and unbruised in a packing plant.