The maximum annual ood level of a river is denoted by H (in meters). Assume that the probability density function of H is described by the triangular distribution shown below. {a H0 a) Determine the ood height Inc which has a mean recurrence interval (return period) of 20 years. b) What is the probability that during the next 20 years the river height H will exceed I120 at least once? c) What is the probability that during the next 5 years the value of I120 will be exceeded exactly once? d) What is the probability that has will be exceeded at most twice during the next 5 years? 5 a 7 I'll\