How is the probability theory related to finance?

the theory of probability deals with statistics.it shows how events that has more than one data can be selected or determined. it can be related to financial management. in the area of investment appraisal. before an investor starts up a project or investment he must first check or test the different projects that can yield the maximum profit. he may use the IRR , ARR,payback period, profitability index, etc project or investment should be done on random selection it should undergo certain evaluations in other not to waste the scarce resources