Suppose a financial analyst is tasked with forecasting the future performance of a company. To do this, they need to make certain assumptions and use various data points to make their projections. However, if there is an unknown or unpredictable event that could significantly impact the company's performance, such as a natural disaster or a major economic downturn, the financial analyst may be unable to use the unknown in their forecasting. In this case, the analyst may need to revise their projections or wait until more information becomes available before making any predictions.