Question

7. A stormwater system is designed to handle 25-year runoff events. Cal culate the probability that over a six year period, the system experi- ences two episodes that exceed the design levels

Answer 1

T = 1/p t = return period 6 = 1/p p = 1/6 = 0.17 probability of non occurrence = 1 - p = q = 0.83 probability of occurrence of event �r' times in �n' successive years = nx_r p^r r^n - r 2 25c_2 p^2q^23 25!/23! Times 2! Times 0.17^2 times 0.83^23 = 0.119 almostequalto 0.12