Explanation:
There is a category of risks that is sometimes called unknown-unknowns, meaning that the risk is not knowable and, therefore, the probability of the risk is also not knowable. Your lead technical advisor becoming seriously ill, your offices being ransacked by
persons engaged in industrial espionage, or one of your subcontractors winning the lottery and running off to the Cayman Islands are all examples of risks that are not known before they occur. However, such risks must be expected and a general contingency
can be set aside to address the impact they leave in their wake.