Geometric probability is a way to compute the probability of uncountable events. To overcome the uncountable nature, the solution is to use area as a computable proxy. Then the ratio of two areas gives the answer we are looking for.

Probability = Area of Qualified Region / Area of Whole Region

Hence, the steps of calculating geometric probability are:

• Draw the whole region which represents all the possibilities
• Draw the qualifed region which contains all the events that meet the requirement
• Compute their area and then the probability

Tips: usually the requirement is given in an inequality expression. Converting such an inequality into an equation gives the boundary condition which can be used to draw the qualified region.